Multiple git hooks running for the same project 

This feature allow users to create multiple git hooks in repositories that do not conflict with gitlab-shell update hook (refs #85, #71, #72, #10, #14)

A ```hook-wrapper``` script is symlinked on repository hook folder. This wrapper symlink have the same name of destination hook (eg ```update```, ```pre-commit```, ...). The hook–wrapper script on execution search for all ```[hookname]-*``` files and execute they. Exit code are reported from wrapper script.

This MR is required to add "git hook management" ([selecting git repo hooks via the gitlab gui](http://feedback.gitlab.com/forums/176466-general/suggestions/4511318-selecting-git-repo-hooks-via-the-gitlab-gui) and [allow new repositories to have default hook script](http://feedback.gitlab.com/forums/176466-general/suggestions/5496298-allow-new-repositories-to-have-default-hook-script)) feature on GitLab (already stubbed, MR in progress).