Handle undefined text area values

Check to see if a text area's `val` is defined before trying to call
`replace()` on it.
Use button type=submit instead of input.
transfer_service_spec: cleanup, merge common code, check against nil

- replace creation of group2 with the use of group without add_owner(user)
- fold TransferService calls into new test function transfer_project
  - remove currently not used (and not working) gitlab_shell stub
    (will submit testcase simulating failure in gitlab_shell separately)
- add checks against not be_nil (result.should be_false passes even if nil)
support latest firefox esr release
Display renamed files in diff views

Show both the old and new filenames when viewing the diff for a renamed
file.
Add option to keep repo on project delete

Update the project API controller to use `Projects::DestroyService`
instead of calling `Project#destroy` directly.

Also add an optional parameter, `:keep_repo`, that allows a project to
be deleted without deleting the repository, wiki, and satellite from
disk.
Use Gitlab.config instead of Settings everywhere
clarify when database.yml needs to be updated

Clarify that database.yml should be updated if you are running a MySQL Database. Remove wording that de-emphasises importance of update.
stop gitlab before mysql optimizations, run checks

Update MySQL optimizations to reflect doing updates after GitLab has already been started back up.
actually give command necessary to update unicorn

Give command to update unicorn.rb rather than just say you need to do it.
stop gitlab before backup

Stopping gitlab before backup ensures that backup has everything before upgrade incase something goes wrong. Also remove extra cd.
stop gitlab before backup
add missing configure Redis to use sockets

Add details from 7.2-to-7.3.md. Replaces https://github.com/gitlabhq/gitlabhq/pull/8047.
add optimizations for mysql to 6.x->7.4 guide

Add mysql optimizations from 7.3-to-7.4.md.
Factor abilities methods

in app controller, user model and services.
Ask the wiki repo, not Gollum, if it's empty

We need to skip empty repositories when creating a backup. Before this
change, we were asking gollum-lib if the wiki contains any _pages_. Now
we ask gitlab_git if the repository contains _files_. This should
resolve gollum_lib Grit timeouts in the backup script.
Fix group user removal from admin area

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add tests for remove group member feature in admin area

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Prevent redeclaration of LDAP strategy
Default the LDAP server label to LDAP