Upgrade to OCMock 2.2.4.  It has some bug fixes, and some enhancements.  Updated some usages of OCMOCK_VALUE, and also updated one unit test which failed (mainly because mock objects return the original class from the -class method now).
Merge pull request #2094 from carllindberg/UpgradeOCMock224

Upgrade to OCMock 2.2.4.