Use instance methods for system_hooks_service

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Convert TestHookContext into TestHookService. Added tests

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

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

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

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'refactoring/services' of /home/git/repositories/gitlab/gitlabhq
Merge branch 'master' of github.com:gitlabhq/gitlabhq