Add RunLocalHooks decorator

Add the RunLocalHooks decorator, that allows the execution of hooks
locally. Also, add a RunLocalHooks method to HooksRunner, to adapt the
signature of HooksRunner.RunHooks to the one expected by HooksMaster,
and also to check that the hooks are being executed locally.

Signed-off-by: Andrea Spadaccini <spadaccio@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>