Remove Javadoc, move to Jenkins instead

A always up-to-date Javadoc can be found at http://jenkins.jselby.net/job/Cubition/javadoc

Having a Javadoc copy on Git can be hard to manage. Instead, the Jenkins server now compiles a Javadoc upon each commit, removing the need for this.

(This is a series pull requests, shame I cannot do it in one)