Add envrc to git-ignore

envrc files are created when you use direnv (Its recommended in
combination with spring, see: https://github.com/rails/spring#setup)
Add enterprise linux distributions as officially supported.
Respect custom gitlab_shell path in gitlab:gitlab_shell:check task

Prior to this change, if I customized the config value of
`gitlab.gitlab_shell.path`, the check would ignore this value in favor
of `"~<gitlab.gitlab_shell.ssh_user>/gitlab-shell/"` resulting in a
failed check when the configuration was otherwise valid.
Add version_sorter gem
Remove arguments from grouped_options_refs

Must have been left over from a previous revision, but the argument
wasn't used anywhere in the method.
Sort tag names using VersionSorter
Remove extra whitespace
Some people are getting the error 'The remote end hung up unexpectedly' due to large chuncks.
Update changelog.
 Merge branch 'increase-nginx-push-size' into 'master'

Increase Nginx Push Size
 Merge branch 'add-enterprise-linux' into 'master'

Add Enterprise Linux
Merge pull request #6500 from tsigo/natural-tag-sorting

Natural version sorting
Merge pull request #6492 from tsigo/gitlab-shell-custom-path

Respect custom gitlab_shell path in gitlab:gitlab_shell:check task
Merge pull request #6480 from jvanbaarsen/add-envrc-to-ignore

Add envrc to git-ignore
Merge branch 'master' of dev.gitlab.org:gitlab/gitlabhq
Merge branch 'master' of github.com:gitlabhq/gitlabhq