Completed Asana tasks:
* #5705476511202
Completed Asana tasks:
* #6057143026589

Details:
To enable backward compatibility with Enrtyption/Decryption algorithm of PubNub 3.3 you have to place
inside your project's .PCH file

Unit testing:
* new test for PNCryptoHelper
Merged with master
Merge branch 'asana-6057143026589' of https://github.com/pubnub/objective-c
Added ability to change cipher key w/o creation of new PNConfiguration instance. Don't forget to set updated configuration to PubNub
Merge branch 'asana-6057143026589' of https://github.com/pubnub/objective-c
Added 3.3-style bc crypto handling
APNS Video demo lib update