Updated static library settings

I ran into some issues when building the project as a static lib. The changes made include some cleanup, some best practice build settings for external static libs as well as suggestions made by Apple for static libs (https://developer.apple.com/library/ios/technotes/iOSStaticLibraries/Articles/configuration.html).

The library, when linked statically, should be included with `#import "MagicKit-iOS/MagicKit.h" (as suggested by Apple).

This builds successfully with Xcode 6.1. I changed the target to iOS 7.0, but this is probably completely unnecessary. Also, the Cocoa libs are not loaded. I haven't build anything for Mac OS X, so I'm not sure how to guard against loading it when building iOS projects. If you want to use it for Mac OS X, all you should need to do is uncomment <Cocoa/Cocoa.h> in the pch file.

My app, Buffer Editor, now uses this lib in production. Thank you for all your hard work!