Fix #3357

* fix: Crippled diff (#4726)

* Regenerate css

- Move Screenshots to Bottom

in browser saw `/repos/{owner}/{repo}/branches/{branch} List a repository's branches` fixed

Addresses https://github.com/go-gitea/debian-packaging/pull/1

Fixes https://github.com/go-gitea/gitea#4892

This change makes it easier to customize the header and footer content. Before this change, the whole header and footer had to be overridden, including the meta, style and script tags.
Signed-off-by: Lukas Bestle <mail@lukasbestle.com>

* Fix redirect with non-ascii branch names (#4764)

* Add integration tests for non-ascii branch redirect

* Fix mysql test and coverage test

GitLab CE doesn't support multiple assignees for issues.  
That's an enterprise feature.  See: https://docs.gitlab.com/ee/user/project/issues/multiple_assignees_for_issues.html

Signed-off-by: Nicolas Lenz <nicolas@eisfunke.com>

The feature to list commits from a subdirectory is already there but
so far the history link to it was missing. There is a History button
in the view_file.tmpl already so avoid showing two history buttons in
that case.

The GitHub webinterface has the same History button in the same place
so this makes gitea a little bit more compatible.
Signed-off-by: Bernhard Froehlich <decke@bluelife.at>

* Minor fix to TRANSLATORS

Replaced @ with AT and removed " accidentially put in few lines

* Update TRANSLATORS

* Make reverse proxy auth optional

If the option ENABLE_REVERSE_PROXY_AUTHENTICATION is enabled, make
reverse proxy auth optional, instead of failing if the authentication
did not succeed.

Fixes #3973
Signed-off-by: Najib Idrissi <najib.idrissi.kaitouni@gmail.com>

* Update http.go

As we've dropped support for go 1.8 (see 1.5.0 release post),
now we need to ensure that a minimum of go 1.9 builds correctly.