Use custom tray icon instead of GTK stock

Use the "Anonymous Cards" image from openclipart.org
(http://openclipart.org/media/files/Anonymous/12230)

This same image is used in other new FPDB icons, but the combinations
with looking-glass don't look good in systray. This icon is plain enough
to work properly even when scaled really small.

setup.py

@@ -15,7 +15,9 @@ setup(name = 'fpdb',
             ['docs/readme.txt', 'docs/release-notes.txt',
             'docs/tabledesign.html', 'THANKS.txt']),
         ('/usr/share/pixmaps',
-            ['gfx/fpdb-icon.png']),
+            ['gfx/fpdb-icon.png', 'gfx/fpdb-icon2.png',
+             'gfx/fpdb-cards.png'
+             ]),
         ('/usr/share/applications',
             ['files/fpdb.desktop']),
         ('/usr/share/python-fpdb',