This PR fix the avatar bug described in #1114. This will fix random avatar is blank problem and potential delete avatars dir problem.

* Add api url func.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* fix: Add unit testing.

* fix: conflicts

* fix: remove trim

* fix: revert test function name.

* don't rewrite non-gitea public keys

* add comment for public key

* remove unused vars

* remove unused comment

* bug fixed for org avatar caused by #1049

* use isfile only

* fix: Admin can see all private repositories on Explore page.

* refactor: fix session

* fix avatar enumable

* fix import style

* move all push update to git hook post-receive and protected branch check to git hook pre-receive

* add SSH_ORIGINAL_COMMAND check back

* remove all unused codes

* fix the import

Add "mirror" field to repo API

* refactor for searching user

* fix like bug

* better format for builder cond

Amended with string to bool change in API SDK.

Signed-off-by: Andrew Boyarshin <andrew.boyarshin@gmail.com>

use terms instead of fields as variable name to avoid confusion: NewPhraseQuery(terms []string, field string)

* git: delegate all server-side Git hooks (#1623)

* create hooks directories

* take control hooks back

* fix lint

* bug fixed and minor changes

* fix imports style

* fix migration scripts

* refactor for issues loadattributes of a repository

* refactors

* fix: Wrong repo list on Explore page if user already loggin.

* fix: code readable.

* fix: declare variable

* initial stuff for oauth2 login, fails on:
* login button on the signIn page to start the OAuth2 flow and a callback for each provider
Only GitHub is implemented for now
* show login button only when the OAuth2 consumer is configured (and activated)
* create macaron group for oauth2 urls
* prevent net/http in modules (other then oauth2)
* use a new data sessions oauth2 folder for storing the oauth2 session data
* add missing 2FA when this is enabled on the user
* add password option for OAuth2 user , for use with git over http and login to the GUI
* add tip for registering a GitHub OAuth application
* at startup of Gitea register all configured providers and also on adding/deleting of new providers
* custom handling of errors in oauth2 request init + show better tip
* add ExternalLoginUser model and migration script to add it to database
* link a external account to an existing account (still need to handle wrong login and signup) and remove if user is removed
* remove the linked external account from the user his settings
* if user is unknown we allow him to register a new account or link it to some existing account
* sign up with button on signin page (als change OAuth2Provider structure so we can store basic stuff about providers)

* from gorilla/sessions docs:
"Important Note: If you aren't using gorilla/mux, you need to wrap your handlers with context.ClearHandler as or else you will leak memory!"
(we're using gorilla/sessions for storing oauth2 sessions)

* use updated goth lib that now supports getting the OAuth2 user if the AccessToken is still valid instead of re-authenticating (prevent flooding the OAuth2 provider)

* Protected branches system

* Moved default branch to branches section (`:org/:reponame/settings/branches`).
* Initial support Protected Branch.
  - Admin does not restrict
  - Owner not to limit
  - To write permission restrictions

* reformat tmpl

* finished the UI and add/delete protected branch response

* remove unused comment

* indent all the template files and remove ru translations since we use crowdin

* fix the push bug

* make xorm log configable

* bug fixed for other sub commands except web

* rebase and fix xorm log

* bug fix for TrimSpace

* fix all the bugs in issues and pulls on dashboard

* small fix and refactor

* add method getRepoIDs for IssueList

* Small opitimization for getUserTeams

* more compact