Add all bindings as a submodule of the main vlc git tree.

Add all bindings as a submodule of the main vlc git tree.

Some basic information about git submodule:
 * by default the submodules are not clone
 * by default the url for the submodules are git:// and not ssh://, the
developpers must change this (just uncomment the right line in .gitmodules)
to be able to commit to the bindings.

Git commandes:
 * git submodule init => intialize the submodules
 * git submodule status => status of the submodules
 * git submodule update => update all submodules