Root project gradle build and TravisCI

[jtwalraven]

• Cleaned up the main project folder (moves examples into directory)
• Created root gradle project (removed old gradle wrapper)
• Added TravisCI file
• Updated Readme with TravisCI badge

The TravisCI script is minimal for now, because TravisCI builds need to be turned on by the project owner @ErnestOrt

[jtwalraven]

Once we get this running properly, I hope to add a linter, testing, and artifact publishing (releases).

[jtwalraven]

This should wait for #65