pep8 fixes

[horkana]

I was thinking it would be useful to have a plugin manager. I wondered if anyone had made one already and was lucky to find your Install plugin, created very recently it seems. So I tried out the code and while reading it made some small changes and then ran pep8 on the code and made lots more minor changes.

I hope you'll accept my code. (It is yours to do with as you please, under any license or copyright, should you ever want to relicense your code, not that such small changes should matter anyway. I try to use the ISC license that OpenBSD prefers, or other MIT/BSD style licenses.)

Summary of changes:
pep8 cleanup (on install_it.py, on made small changes to the other files)
http://pep8online.com/
variables to avoid repetition
shorter menu label
"..." in menu label to indicate further input is required
minor consistency fixes
commented out unused imports (manually, didn't use an automatic checker so hope I haven't made a mistake, all seems to still work fine though)

other notes:
the message shown is a bit scary, it looks like an error message. even though the plugin has worked successfully.
at first I thought the plugin had failed to install.
also maybe the message should mention the "plugin will be available when you next start the program"?
wasn't sure yet about how best to improve it so left it as is.

I look forward to using your install it plug-in (maybe eventually I'll get around to writing a more complicated plugin manager myself, would like to be able have a plugin manager to track what is most or least used and allow me to easily disable them, but that's for another time). Thanks.