fixes a bug uncovered while debugging an issue with a plugin crashing the websocket connection. the crash ended up being the result of a plugin returning a reading whose value was encoded as bytes. bytes are not JSON serializable, so synse-server was failing the read and terminating the websocket connection. this change checks for bytes and decodes to a string, then tries to load the string as JSON, keeping the result if it renders to a list or dict.
This PR:
VIO-1238