update aerogear-ios to target iOS 7

done for [AGIOS-157](https://issues.jboss.org/browse/AGIOS-157)

note:
  - Kiwi framework latest release expose a bug causing test cases to fail when run on 64bit. The issue has been already fixed [Kiwi/#370](https://github.com/allending/Kiwi/pull/370), but till their next release, Podfile points to their 'master' branch.