can-utils: new package

CAN userspace utilities and tools (for use with Linux SocketCAN).

There is no real "homepage" for this project (the only thing I could
find was the gitorious page) and they haven't produced any proper
releases (source archives and/or git tags), even though git history goes
back to 2006 and things seem stable.
Revert "Update BadVPN"

This reverts commit 53f4bf3241729708b803611de1394421b4dbafb4.

Because it creates an evaluation error:

  error: while querying the derivation named `badvpn-http://badvpn.googlecode.com/files/badvpn-openwrt.tar.bz2':
  invalid character `:' in name `badvpn-http://badvpn.googlecode.com/files/badvpn-openwrt.tar.bz2'

It looks like some auto-updater script failed, because the version
attribute is not supposed to go from

  version="1.999.128";

to

  version="http://badvpn.googlecode.com/files/badvpn-openwrt.tar.bz2";