Enable rubocop metrics
This enables rubocop metrics like CyclomaticComplexity and ABCSize.
Initial threshold values are high, should be probably decreased.
See merge request !1802
UI: Add "New X" buttons to dashboard and group issue, MR and milestone indexes
# To do
- [x] Use searchable dropdown since dashboard/group can have a lot of projects. Use select2?
## Before

## After

As you can see, for milestones, groups are listed as well as we can now easily create group milestones.
Fixes#3544 and https://dev.gitlab.org/gitlab/gitlabhq/issues/2581
See merge request !1968
Added 3 rake tasks for repository maintainance
## What does this MR do?
This MR adds 3 rake tasks
- gitlabrepack
- `-a`
- `--quiet`
- gitlabgc
- `--auto`
- `--quiet`
- gitlabprune
- Needs git version > 1.8.4.1, Ubuntu repos @ 1.9.x
## Are there points in the code the reviewer needs to double check?
AFAIK this MR abides by the Guidelines for shell commands. Also, the output given is not the diskspace saved etc, just if the commands were succesfull. (Parsing output etc did not seem like the way to go)
Output might be verbose when a lot of repo's are in the system?
## Why was this MR needed?
`git gc` and `git prune` can reduce storage space used.
## What are the relevant issue numbers / Feature requests?
Closes#1529
## Screenshots (if relevant)
`rake -T`

(git fsck now removed as IMHO it doesn't add any value.)
See merge request !1388
Fix signin with OmniAuth providers
OmniAuth CSRF protection was broken with the move to Rails 4.2 since
the CSRF logic in Rails changed.
This new implementation calls out to Rails instead of copying its code,
which is far easier to maintain.
See merge request !2019
Fix API setting of 'public' attribute to false will make a project private
There is a bug in the projects API where setting `public` to `false` of would not change `visibility_level` even if `visiblity_level` were not present.
Closes#3864
See merge request !1996