Some minor tweaks, as discussed in ticket 225.

1) Fixed wording on the -U option
2) Added a -K option to keep temporary files
3) Some tweaking with Ubuntu repository setup (11.04 logic seems to be off with respect to the -y choice). Made the adding of the universe dependent on it not being already there.

Open question… for older Ubuntu versions the archive location added for the universe seems wrong. The one I know is:

deb http://old-releases.ubuntu.com/ubuntu/ natty main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-security main restricted universe multiverse

However, I did not change the code at this point as that seems like it should be tested independently (maybe my expectations here are off).