Add ByteRange/StringPiece Conversion for Cython
Add ByteRange/StringPiece Conversion for Cython

Summary:
Moving the cython definition to folly/python.
Adding simple conversion helper to_bytes

This is to cut down on duplicate folly::range cython definitions

Reviewed By: yfeldblum

Differential Revision: D6291125

fbshipit-source-id: 314b732a1516a03fb5c9a57939552bbabd81970b

rklabs/folly,rklabs/folly,Orvid/folly,facebook/folly,rklabs/folly,rklabs/folly,Orvid/folly,facebook/folly,Orvid/folly,rklabs/folly,facebook/folly,Orvid/folly,facebook/folly,facebook/folly,Orvid/folly