Feature solap4py script

This pull request adds auto-installation, starting and stoping of the solap4py-java to geonode's pavement script.
Running a ``paver start`` will retrieve solap4py-java and build it if needed, then start geonode and solap4py-java.
Running a ``paver stop`` will stop geonode as it did but it will also stop the solap4py-java server.

There's also two new tasks to start and stop the solap4py server manually, ``paver start_solap4py`` and ``paver stop_solap4py``.