Update to version 0.5

Changes:
• fixed a bug when value is set to 0
• updated preferences
• updated version info to run on Gnome Shell 3.6

tested with Gnome Shell 3.4 on Fedora 17

remaining Bug: also speeds up logout and shutdown dialog countdown

TODO:
• compile new schema
• release to extensions.gnome.org
• add info on remaining Bug to description on extensions.gnome.org
• add url info to metadata.json