Modify  TRequestsTransport to raise an exception 4xx or 5xx responses.

This changes TRequestsTransport to raise an exception on 4xx or
5xx responses. Previously the TRequestsTransport would ignore those
responses and treat the response as valid. The response would not be
valid JSON and cause thrift decoding errors later on.

Testing Done:
./pants src/test/python/apache/aurora/common:test_transport -v

Bugs closed: AURORA-949

Reviewed at https://reviews.apache.org/r/28451/