Updates for introducing new PushAppID / VariantID (AGPUSH-86)
Removing PUT endpoit for variant instance (AGPUSH-89)
Refactoring: moving impl (service/dao) to IMPL packages
Adding 'public' API interfaces and renaming MobileApp to MobileVariant
refactoring: renaming mobileApp to mobileVariant
Renaming iOSApplication to iOSVariant
Renaming SimplePushApplication to SimplePushVariant
Renaming AndroidApplication to AndroidVariant
Renaming of MobileApplicationInstance to the MobileVariantInstance
Removing unused, abstract, base class
Instance endpoint renmaed
Using ALIAS, instead of clientIdentifier
Changing method names to reflect the spec terminology
Class renaming to better reflect the spec