Move repository when project is removed

Ths commit does next:

* When we remove project we move repository to path+deleted.git
* Then we schedule removal of path+deleted with sidekiq
* If repository move failed we abort project removal

This should help us with NFS issue when project get removed but
repository stayed. The full explanation of problem is below:

* rm -rf project.git
* rm -rf removes project.git/objects/foo
* NFS server renames foo to foo.nfsXXXX because some NFS client (think
* Unicorn) still has the file open
* rm -rf exits, but project.git/objects/foo.nfsXXX still exists
* Unicorn closes the file, the NFS client closes the file (foo), and the
* NFS server removes foo.nfsXXX
* the directory project.git/objects/ still exists => problem

So now we move repository and even if repository removal failed

Repository directory is moved so no bugs with project removed but
repository directory taken. User still able to create new project with
same name. From administrator perspective you can easily find stalled
repositories by searching `*+deleted.git`

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