got rid of SOOM_SEC

CUSTOM_SEC is now SOOMLA_SECRET and it'll be provided straight to Soomla (which is soomla-core). so... the way we initialize now is: [Soomla initialize:@"your secret here"]; [StoreController initializeWithAssets:<your IStoreAssets here>];
Also removed ObsuredNSUserDefaults.
StoreController is now SoomlaStore
Merge branch 'soomlaCore' of https://github.com/soomla/ios-store into soomlaCore

* 'soomlaCore' of https://github.com/soomla/ios-store:
  submodules