Convert to puppet-module-skeleton form

Add tests, separate LICENSE file, remove mentions of @samjsharpe and
make more corporate.
Use stankevich/python to manage pip packages

Very similar to stuff in gds-operations/puppet-graphite#17. Virtualenvs
to come in future commit.
Install into a virtualenv
typo in CHANGELOG version
Merge pull request #2 from alphagov/use-python-module

Install into a virtualenv