Use Accept-Encoding: identity when requesting files
Document why we use decode_response=False
Merge pull request #1688 from dstufft/accept-encoding-identity

Accept encoding identity
Test on Linux and OSX
Exclude tests that don't need to be run on every OS
Switch to language: c and bootstrap a Python environment ourselves
Create a virtual environment
Run tox from inside our virtualenv
Use the default python3 interpreter
Install thw VCSs only if needed