Merge pull request #45 from hgschmie/use-uri

Remove the usage of files in the public API, use URIs everywhere.
- Make the template selection configurable.

- Add a template for immutable classes.
Merge pull request #46 from hgschmie/template-selection-1

- Make the template selection configurable.
Merge branch 'master' of github.com:facebook/swift

Conflicts:
	swift-generator/src/main/java/com/facebook/swift/generator/SwiftGeneratorConfig.java
	swift-generator/src/main/resources/templates/java/immutable.st
	swift-generator/src/main/resources/templates/java/regular.st
	swift-generator/src/test/java/com/facebook/swift/generator/TestSwiftGenerator.java
	swift-maven-plugin/README.md
	swift-maven-plugin/src/main/java/com/facebook/mojo/SwiftMojo.java