#79 - Summary GUI and GNOME 2 panel applet

This adds a GNOME 2 panel applet, and a lightweight summary GUI (`cylc gsummary`) to monitor running suites.

The hosts that are scanned can be configured in an entry in the `site.rc` file - in the case of the summary GUI, also on the command line.

The installation instructions for the GNOME 2 panel applet are in `conf/gpanel/cylc.server`.

@matthewrmshin, please review (@hjoliver, please take a look when/if you can).