- #2153 remove require for gravatar

LDAP parameters UI: bind_dn and bind_password are not required

We only handle branch selection for repo home and commits pages, so the
redirection URL is based on PageIsCommits

I've mostly duplicated the dropdown code from repo/home.tmpl, which
basically only required a change to the URL. This could probably be
broken out into something more modular.

We can look at the PushCommits object to see how many commits were
included in a commit, and add some template logic to only show the
comparison link when there are at least 2 commits in a push. We also
correct the link to display the number of commits.

This commit improves templates readability, since all of them use consistent
indent with all template command blocks indented too.

1. Indents both HTML containers such as <div>, <p> and Go HTML template blocks
   such as {{if}} {{with}}

2. Cleans all trailing white-space

3. Adds trailing last line-break to each file

Most commit in Git are expected to follow standard of single header line,
followed by description paragraphs, separated by empty line from previous block.

Previously Gogs were treating everything as single header. Now we are trying to
render only first line as header, but following lines (description chunks) as a
verbatim.

Current green SHA1 labels are more pronounced than other UI elements attracting
attention as if they were most important thing in the UI, while they are not as
important, especially without real Git client.

Using grey SHA1 labels makes the UI more balanced, less aggressive and lets
user to focus on other content elements.

NOTE: Neither GitHub or Bitbucket uses so heavy pronunciation as Gogs.

Further layout fixes

Merges repo/sidebar.tmpl with repo/header.tmpl and makes every repo page use
middleware.RepoRef() necessary to display information on this menu.

This uses a CSS trick making first th to be relative block with width equal to
first two columns, effectively working around inability to use colspan="2" on
first row that was breaking "fixed-layout" for tables.

Also use grey header for last-commit SHA1 tag.

Just use secondary menu instead custom ".head.meta", which simplifies code.

Also do not display repo URL action when we are in subdirectory or viewing a
file.

This is more inline with way GitHub looks like and feels much more natural and
in style with rest of the interface.

Instead using own ellipsis, uses Semantic UI fixed single line table which
effectively applies ellipsis to all overflowing table cells.

NOTE: File list cannot use colspan="2" for 1st "Last commit" elements,
otherwise layout breaks with fixed table.

Consider following LDAP search query example:

    (&(objectClass=Person)(|(uid=%s)(mail=%s)))

Right now on first login attempt Gogs will use the text supplied on login form
as the newly created user name. In example query above the text matches against
both e-mail or user name. So if user puts the e-mail then the new Gogs user
name will be e-mail which may be undesired.

Using optional user name attribute setting we can explicitly say we want Gogs
user name to be certain LDAP attribute eg. `uid`, so even user will use e-mail
to login 1st time, the new account will receive correct user name.