Add a restart-jobs role

Frequently users want Hydra access just to restart jobs. However,
prior to this commit the only way to grant that access was by giving
them full Admin access which isn't necessarily what we want to do.

By having a restart-jobs role, we can grant this privilege to users
who are known to the community and want to help, but aren't long-time
members.

I haven't tested this commit, but it looks good to me...

src/lib/Hydra/Controller/JobsetEval.pm

@@ -188,7 +188,7 @@ sub cancel : Chained('evalChain') PathPart('cancel') Args(0) {
 
 sub restart {
     my ($self, $c, $condition) = @_;
-    requireProjectOwner($c, $c->stash->{eval}->project);
+    requireRestartPrivileges($c, $c->stash->{eval}->project);
     my $builds = $c->stash->{eval}->builds->search({ finished => 1, buildstatus => $condition });
     my $n = restartBuilds($c->model('DB')->schema, $builds);
     $c->flash->{successMsg} = "$n builds have been restarted.";