Add unixsocketperm note to upgrade guide
Fix 'Invalid socket file permissions' error
Use 'sed' with pre-search to enable only if present in redis config file.
Path on ubuntu is different
Use edit in place with sed instead of tee
Remove obsolete line
Merge branch 'master' into 'master'

Small documentation update, add unixsocketperm

If you run gitlab as user ``git`` while redis runs as user ``redis`` and you add git to ``redis`` group, you'll need to set ``unixsocketperm = 0775`` to grant write access to group.

See merge request !192
Minor UI improvements

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'master' of github.com:gitlabhq/gitlabhq
Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ce