Add columns to store project creation settings

Add project creation level column in groups
 and default project creation column in application settings

Remove obsolete line from schema

Update migration with project_creation_level column existence check

Rename migrations to avoid conflicts

Update migration methods

Update migration method

No-one is allowed to force push to a protected branch, or delete it. That's
correct in the documentation, but was wrong in the drop-down.

this will remove the need make N queries (per-note) at the
cost of having to mark notes with an attribute

this opens up the possibility for other special roles for notes

Use the EnforcedStyleForMultiline: no_comma option.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Changes include:

- Ensure Member.add_user is not called directly when not necessary
- New GroupMember.add_users_to_group to have the same abstraction level as for Project
- Refactor Member.add_user to take a source instead of an array of members
- Fix Rubocop offenses
- Always use Project#add_user instead of project.team.add_user
- Factorize users addition as members in Member.add_users_to_source
- Make access_level a keyword argument in GroupMember.add_users_to_group and ProjectMember.add_users_to_projects
- Destroy any requester before adding them as a member
- Improve the way we handle access requesters in Member.add_user
  Instead of removing the requester and creating a new member,
  we now simply accepts their access request. This way, they will
  receive a "access request granted" email.
- Fix error that was previously silently ignored
- Stop raising when access level is invalid in Member, let Rails validation do their work

Signed-off-by: Rémy Coutable <remy@rymai.me>

NotesHelper#note_editable? and ProjectTeam#human_max_access currently
take about 16% of the load time of an issue page. This MR preloads
the maximum access level of users for all notes in issues and merge
requests with several queries instead of one per user and caches
the result in RequestStore.

This reverts commit 530f5158.

See !4892.

Signed-off-by: Rémy Coutable <remy@rymai.me>

This reverts commit 9ca633eb, reversing
changes made to fb229bbf.

- Cherry-picked from `mvestergaard:branch-protection-dev-merge`
- https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4220

This is a try for a new approach to put the access checks at the service level.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Show permissions for all project.
Add ability to remove user from group if not an owner
Remove unnecessary admin controller