Bump the iOS deployment target to 8.0.

Dynamic frameworks aren’t supported on iOS 7. :(

This change will also allow apps using LlamaKit to be submitted to the App Store. Right now you'd get the following errors on submission/validation:

![screen shot 2014-11-21 at 11 37 46 am](https://cloud.githubusercontent.com/assets/22635/5135955/c514c6e4-7173-11e4-8d9f-dc97880aa6ea.png)

![screen shot 2014-11-21 at 11 38 04 am](https://cloud.githubusercontent.com/assets/22635/5135954/c20d92fa-7173-11e4-910c-fd06cb83293f.png)