* Speed up conflict checking in pull request creation

In order to check conflicts of a PR, we set up a working tree by
cloning the base branch, which is quite time-consuming when the repository is huge.
Instead, this PR uses `git read-tree` and `git apply --check --cached` to check conflicts.

For #258

* Use $GIT_INDEX_FILE instead of --index-output to avoid lockfile problem

The lockfile gets renamed to the final destination after the operation
finishes. But it must be located in the same filesystem, which prevents
us from using /tmp.

* Temporary file names should not prefixed with '-'

Delete old temp local copy before we create a new temp local copy

Also move duplicated code into repo.APIFormat(..)

* Fix #344 (regression in PR-API #248)

Suppress the error when we're removing a file that may not exist

* golint fixed for modules/setting

* typo fixed and renamed UNIXSOCKET to UnixSocket

From code.gitea.io/go-sdk/gitea
  To code.gitea.io/sdk/gitea

# Conflicts:
#	models/git_diff.go
#	models/issue.go
#	models/org.go
#	models/pull.go
#	models/repo.go

- Update import paths from github.com/go-gitea to code.gitea.io
- Fix import path for travis

See https://docs.travis-ci.com/user/languages/go#Go-Import-Path

See https://github.com/golang/go/wiki/CodeReviewComments#mixed-caps

Replaced gogits go-gogs-client with go-sdk

Still use GOGS_WORK_DIR and GOGS_CUSTOM env variables
as a fallback if the equivalent GITEA_* are not set,
warning user about the need for change.

Does not change "gogs" to "gitea" in webhook type name
Because "gogs" hook type is part of the API (routes) and used
in templates...

Closes #87

* Replace gogits/git-module dependency with go-gitea/git

Fixes #92

* Remove git alias for git module import (not needed)

- Fill Milestone and Assignee field when available in webhook payload

commit 0afcb843d7
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 17:13:29 2016 -0600

    Removed Upload stats as the upload table is just a temporary table

commit 7ecd73ff55
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 08:42:41 2016 -0600

    Fix for CodeMirror mode

commit c29b9ab531
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 08:03:33 2016 -0600

    Made tabbing in editor use spaces

commit 23af384c53
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:56:46 2016 -0600

    Fix for data-url

commit cfb8a97591
Merge: 7fc8a89 991ce42
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:42:53 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	public/js/gogs.js

commit 7fc8a89cb495478225b02d613e647f99a1489634
Merge: fd3d86c c03d040
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:40:00 2016 -0600

    Merge branch 'feature-create-and-edit-repo-file' of github.com:richmahn/gogs into feature-create-and-edit-repo-file

commit fd3d86ca6bbc02cfda566a504ffd6b03db4f75ef
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:39:44 2016 -0600

    Code cleanup

commit c03d0401c1049eeeccc32ab1f9c3303c130be5ee
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 29 15:38:23 2016 -0600

    Code cleanup

commit 98e1206ccf9f9a4503c020e3a7830cf9f861dfae
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 18:36:01 2016 -0600

    Code cleanup and fixes

commit c2895dc742f25f8412879c9fa15e18f27f42f194
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 18:24:04 2016 -0600

    Fixes per Unknwon's requests

commit 6aa7e46b21ad4c96e562daa2eac26a8fb408f8ef
Merge: 889e9fa ad7ea88
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 17:13:43 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	modules/setting/setting.go

commit 889e9faf1bd8559a4979c8f46005d488c1a234d4
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:09:18 2016 -0600

    Fix in gogs.js

commit 47603edf223f147b114be65f3bd27bc1e88827a5
Merge: bb57912 cf85e9e
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:07:36 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	public/js/gogs.js

commit bb5791255867a71c11a77b639db050ad09c597a4
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:02:18 2016 -0600

    Update for using CodeMirror mode addon

commit d10d128c51039be19e2af9c66c63db66a9f2ec6d
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Tue Jul 19 16:12:57 2016 -0600

    Update for Edit

commit 34a34982025144e3225e389f7849eb6273c1d576
Merge: fa1b752 1c7dcdd
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Tue Jul 19 11:52:02 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go

commit fa1b752be29cd455c5184ddac2ffe80b3489763e
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 15 18:35:42 2016 -0600

    Feature for editing, creating, uploading and deleting files

Unix() already uses UTC as timezone

RepoLink -> Link, RepoRelLink -> RelLink, FullRepoLink -> FullLink