Update git hooks every time shell starts

Check for projects if they have a 'tools/git-hooks' directory. If they have,
make sure all of it's hooks are on '.git/hooks'.
The option '-u' says to cp to only copy if the destination file is older than
the source of it it doesn't exists.

Change-Id: Ia377f37810ad1fe1bcc77323756f3dff3b240940