Use similar interface to access gitolite

Simplified gitolite handle logic
Stubn over monkeypatch
Stub only specific methods in Gitlab:Gitolite
Moved grach auth to lib
added specs for keys observer
removes SshKey role

app/models/key.rb

@@ -1,7 +1,6 @@
 require 'digest/md5'
 
 class Key < ActiveRecord::Base
-  include SshKey
   belongs_to :user
   belongs_to :project
 
@@ -50,6 +49,10 @@ class Key < ActiveRecord::Base
       user.projects
     end
   end
+
+  def last_deploy?
+    Key.where(identifier: identifier).count == 0
+  end
 end
 # == Schema Information
 #