AGPUSH-997: provide meaningful message when APNS certificate is not valid
AGPUSH-997: provide meaningful messages to all constrainst in Variants
AGPUSH-997: make iOSVariant.production required parameter on UI
added certificate bean validation test
Merge branch 'AGPUSH-997-invalid-ios-variant'
AGPUSH-1132: UI does not allow to create variants other than iOS - Add button disabled
AGPUSH-748: adopt angular 'controller as' syntax for clarity
AGPUSH-748: put each Angular controller to separated source file
AGPUSH-986: refactor endpoints + separate each module to own source file
AGPUSH-1096: allow to generate push-config.json for selected variants
fixed jshint errors