Bump dependency on overlay

Make react-native libs (not react-native itself) dependencies instead of

peer

peerDependency everything!

Bump dependency versions

Only include necessary files in npm package

Make react-native a peerDependency

Bump for react-native 0.4.0

Properly require overlay in xcodeproj

Bump version

Add support for modifying the default styles.

- Remove default alignItems: 'center' on container
- Remove default alignSelf: 'stretch' on modal