Swift 1.2 compatibility

[kwhitaker]

Hello,

I updated XCode to 6.3 today, which includes Swift 1.2, and that seems to have broken Armchair. Several of the errors I think I was able to fix myself (implicitly casting NSString into String is no longer allowed, it seems), but I'm getting a few errors which, frankly, I'm not knowledgable enough to fix.

All of these are in Armchair.swift, so far.

1. public class StandardUserDefaults: ArmchairDefaultsObject renders "Type StandardUserDefaults does not conform to protocol ArmchairDefaultsObject.
2. private var userDefaultsObject:ArmchairDefaultsObject? = StandardUserDefaults() renders "StandardUserDefaults is not convertibel to ArmchairDefaultsObject?"
3. let currentVersion = NSBundle.mainBundle().objectForInfoDictionaryKey(kCFBundleVersionKey) as? NSString renders "Type of expression is ambiguous without more context."

I'm going to do my best to get some answers for these, but I thought it might be helpful for you to know (and maybe you have some quick solutions).

[coneybeare]

Thanks for digging in. I am not going to be able to work on Armchair for a bit, so any PR's would be much appreciated. Thanks for the heads up.

[nickoneill]

Added in #12