Make MagicalRecordInternal.h public

Yes, it's a bad filename
Do the weak/strong dance so that the weak reference to self isn't unpredictably set to nil
Silence warnings about the entityName method not being implemented by this translation unit
Rejig the advanced save options so that they're nicer to use under Swift, and work around some warnings in Xcode 6.1
Xcode 6.1 upgrade checks
Resolve more warnings around ambiguous method resolution
Add workaround for Travis builds failing — see https://github.com/travis-ci/travis-ci/issues/2836
Check for NSMigrationError alongside NSPersistentStoreIncompatibleVersionHashError and NSMigrationMissingSourceModelError
syncing with magical panda