Add support for Google App Engine

[jeshan]

Please implement Serializable on all your classes.
And also, Animation objects may exceed 1MB in size, which is not allowed in memcache in Google App Engine. In this case, a terminal error is thrown through Vaadin and which is hard to recover from in the application.

[jouni]

Added serial version uuid's in 318430f

New version will be in the Directory shortly.

I didn't have time to investigate the Animation object size, so that's unfortunately still unresolved, and I'm keeping this issue still open.