master.cfg fine-tuning for Qt Mountain Lion Release bot
https://bugs.webkit.org/show_bug.cgi?id=113191

Reviewed by Ryosuke Niwa.

* BuildSlaveSupport/build.webkit.org-config/config.json:
  - Rename the slave due to its location change.
  - Update the platform of the slave.
* BuildSlaveSupport/build.webkit.org-config/master.cfg:
(RunQtAPITests): Enable running WK2 API tests on Qt.
(RunQtAPITests.start):
(RunWebKit2Tests.start): Force pixel tests on the Qt Mountain Lion Release builder.
(BuildAndTestWebKit2Factory): Added. (Build WK1 and WK2 too, but run only WK2 tests.)

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146989 268f45cc-cd09-0410-ab3c-d52691b4dbfc