Allow methods that take a class name to also take the class object #20
Description
For example, let WMObjectContext's entities:matchingQualifier: method be called these two ways:
var results = [oc entities:"FooEntity" matchingQualifier:[WMKeyValueQualifier key:"banana = %@", 3]];
or
var results = [oc entities:FooEntity matchingQualifier:[WMKeyValueQualifier key:"banana = %@", 3]];