First naive implementation of the RayTracerDemo in Java/GWT

The implementation is split into 3 packages (client, shared and server).
The Client package contains the GWT relevant code and the Server package the pure java code.
The Shared package contains classes that are shared in both implementations (i.e. Vector3f, etc)

The project is mavenized. To compile both GWT and Java just run mvn clean compile gwt:compile

The Java version can be started with java -cp target/classes/ io.github.timeu.javagwtraytracerdemo.server.App.

For the GWT version just go into the web folder and run SimpleHTTPServer (python -m SimpleHTTPServer).

To compile
Merge pull request #6 from timeu/master

First naive implementation of the RayTracerDemo in Java/GWT (thanks to timeu)