Eagerly consume a stream when exposing to caller.

HTTP responses return an input stream wrapped in a TypedInput which we pass to the converter for deserialization as fast as the bytes come in. If we are skipping the converter (non-2xx resposne code) or returning the response directly we eagerly consume the stream to a byte[] for the caller.

If the converter threw an exception while reading the stream then it is nulled out before being handed to the RetrofitError. This prevents partially read streams from being exposed.

Closes #181.