Unique indexes

Hey, you had a bug: unique indexes were created as non-unique, so I added the @"UNIQUE" part.

Also, this can be a personal style, but I think  `[NSArray componentsJoinedByString:]` is cleaner of `[NSMutableString appendString:]`. It's definitely cleaner than the enumeration. Feel free to change that though ))

I think it doesn't update the pod unless we bump version. I'm new to CocoaPods though.

Thanks, Ilya.