Support IBDesignable and Swift

- Added support for the `IBDesignable` annotation by specifying which bundle the NIB should be loaded from. It's a good assumption that the NIBs are located in the same bundle as the class itself.
- Also added support for Swift by making sure the module name is not considered when creating the default NIB name.
Merge pull request #8 from ribot/feature_ib_designable_support

Support for IBDesignable and Swift