pyupdatesd: A Yum Updates Tray Icon for XFCE

[Noah Petherbridge]

Hey,

I've moved my pyupdatesd script to GitHub: 
https://github.com/kirsle/bin/blob/master/pyupdatesd - so, git pull 
requests are welcome if anyone has any tweaks they'd like for this script.

I've added a few features to it, in the form of command-line options:

* You can set/override the $DISPLAY for X11 by using the --display 
option (useful if you launch the script from an environment where 
$DISPLAY isn't set).
* Debug mode with --debug will make the script print things verbosely 
(including the exit status code and output from `yum check-update`)
* Testing mode with --testing will force the script to disregard the 
output from `yum check-update` and pretend that it returned with code 
100 (indicating updates are available), so the script will show the icon 
and notification pop-up.

I've also made the script schedule its first update check for "now" on 
startup, so you don't have to wait 15 minutes to get the first 
notification to appear.