Provide scripts for installing and running txircd standalone

Since Ashton asked about this, I wrote a few scripts to make running txircd standalone a bit more convenient. It handles setting up the virtualenv and provides an easy way to start and stop the deamon. It assumes python2-virtualenv, as well as the requirements for the dependencies txircd uses (these being a C compiler for Twisted, python2-dev, libssl-dev and libyaml-dev), are already installed on the system.
If it will work as a virtualenv arg, "/usr/bin/env python2" is the standard way to do this.
It will pick up python2 wherever it is installed, as long as it's in the path.
Although, I would expect that is exactly what 'python2' alone does, too.