Correctly encode JSON payloads as bytes (fixes #100)
Correctly encode JSON payloads as bytes (fixes #100)

With Python 3, zlib expects a bytes object passed in to zlib.compress().
When using the JSON ingest client, we need to encode or JSON strings as
UTF-8 bytes before passing them to the _post() method.

signalfx/signalfx-python,signalfx/signalfx-python