Removed check for self.managedObjectContext
Created Assertion if init is called on MDMPersistanceController .. as object instantiation needs to created using one (of the two) designated initializers
Using ALog instead of ZAssert in case of instantiation using `-(instanceType)init`
Merge pull request #23 from mattglover/remove_check_for_MOC_instance_variable

Remove check for MOC instance variable in `saveContextAndWait:..`