Add dead simple README for pygeoip developers

DEVELOPER

+Bootstrap manual for developers of pygeoip
+
+Dependencies: tox, nose, epydoc, six
+
+For testing we are using tox virtualenv-based Python version testing
+and nose as test framwork.
+
+Tox will create virtualenvs for all Python version pygeoip supports
+and installs the current working tree using the setup.py install script.
+Running the tests requires a couple of sample databases found on the
+link below.
+
+Maxmind sample databases for testing can be downloaded here:
+http://www.defunct.cc/maxmind-geoip-samples.tar.gz (58 MB)
+
+Extract the tarball in the tests directory and run tox from the root directory.
+
+Please make sure your code passes all tests before opening pull requests.
+
+All the best,
+William Tisäter