Ability to skip a particular repository while using wildcard

[sbadugu]

I like the fact that one can sync up labels for all the repositories under an organization at one go. But, it would be nice if there is a feature added to omit one or more repos while using the wildcard.

For e.g. ./github-sync.php sync piwik/piwik "piwik/*" -"piwik/nochanges"