misc: remove files that are elsewhere.

.reg is in gist and others in shell-things.
misc: rm sources.list.ubuntu1304

Not supported.
misc/sources.list.ubuntu*: clear a little.

According to https://help.ubuntu.com/community/UbuntuBackports ,
backports are enabled by default, but nothing is installed from there
unless otherwise specified.

Virtualbox and MATE aren't required either.
misc/sources.list.ubuntu*: remove *.asc

I just broke my signature anyway and I believe that my signature is
invalid.
misc: rm sources.list.mint* && remove vbox & mate.

From not-removed files in this commit.
misc: remove *.asc

They just became invalid. I will sign them at home.