Ignore pyc and egg files

The `setuptools` package likes to install things into the project root,
and we like to ignore these generated files. Therefore, ignore compiled
Python and egg files.
Use nose to run tests and document this

Tests can be run using `python setup.py test` now; this uses nose, which
is rather smart.

It's a simple two-step process to get the library's tests running, but
you have to know the two steps. This is now in the README.