Releasing to pypi again!

Our release cycle was broken since 3.1.5, hence you can not find the previous releases on pypi. We now fixed the problem.

• #129, #128 fixed
• Adds optional token amount limit per user
• Changelog and Readme converted to markdown
• Auth header prefix is now configurable
• We ensure not to have flake8 errors in our code during our build
• MIN_REFRESH_INTERVAL is now a configurable setting