Allow excluding paths from package

Summary: Resolves T2149.

Test Plan:

$ bin/storage upgrade

1. /owners/ - saw +
2. /owners/package/1/ - saw +
3. /owners/edit/1/ - added exclude paths, saw correct e-mail
4. /rPabc123 - included paths are still highlighted and excluded not
5. /owners/view/search/?path=/included/ - found
6. /owners/view/search/?path=/excluded/ - not found
7. owners.query - path: /included/
8. owners.query - path: /excluded/
9. new unit test
   
   PhabricatorOwnersPackage::loadAffectedPackages( $repository, array('/excluded/b.php'));
   
   PhabricatorOwnersPackage::loadAffectedPackages( $repository, array('/included/a.php'));

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2149

Differential Revision: https://secure.phabricator.com/D4102