Matplotlib GTK and X11 forwarding fixes

This is the latest stable version for the HeliPlot package. Matplotlib gtk toolkit errors have been fixed with updated matplotlib explicit method calls, and X11 forwarding has been solved with exporting the physical display id to the cronjob.
Known issues that will be fixed after this merge:
1.) Pulling metadata for station names and info from seed files. Seed files have different formats, previous seed files contain empty blockettes, this will be solved with a script from Adam Ringler that pulls metadata from mulitple seed formats
2.) X11 forwarding on remote server does not work when the user is logged out. Physical display is not seen when the user is not logged in, obspy.matplotlib needs a physical display in order to create image files. However, since we are only creating  image files there is no need to use a physical display, the fix will be issued with a matplotlib backend that does not depend on a physical display to create image files.