Removing ruptures phase 2

This pull requests remove the ruptures as pickled objects from the database (bug https://bugs.launchpad.net/oq-engine/+bug/1277354). This is possible because it also removes the GMF-on-the-fly feature.
Notice that surface, lons, lats and depths stay in the db as pickled columns of the table SESRupture. They will removed in future pull requests.