First bits for having a configuration and admin settings page.
New libraries for configuration and admin page.
Can now correctly load a "hello world" settings page.
- Fixed positioning of plugin's setting page between other pages.
- Experimenting with JSP.
Controller for handling requests, plus some refactoring.
- We will use our own configuration class. Seems like one's not supposed
to use MainConfigurationProcessor and it's unclear as to when writeTo
will be invoked. 
- Extended the configuration page.
Configuration can now be loaded and saved.