Added PPA confirmation option for 12.04, added option for keyserver, fix pp...

...a normalization for lucid and precise.

Normalization now works on 10.04 **and** 12.04 so I closed #70 and #71.

As for 10.04, not sure how we want to handle the confirmation, as there is no option like you mentioned before.

For now, if on ubuntu >= 12.04, it confirms by default.

For the key server, I made sure that if they tried to pass multiple key servers, to just grab the first one (instead of erroring), but it may not be needed.

Feedback welcome, thank you !

@joshuatobin participated in this PR.