Create CONTRIBUTING.md

Partly inspired by and copied from https://github.com/puppetlabs/puppet/blob/master/CONTRIBUTING.md
Update CONTRIBUTING.md

Fix my Markdown :D
fixes #172
hopfully it's now more pythonic :D
bug fixes
Increase URL robustness by allowing useless query arguments
Force explicit encoding on source code download, fixes #173
Update README.rst
wat
Test improvements
This might end badly
Merge remote-tracking branch 'samsemilia7/myfeature' into develop
Code formatting
Fix migration script