0.3.0

Changes:

• Implement basic integration testing with low coverage initially
• max_bytes was incorrectly associated with max_msg_size, we now default to 1GB for the former and 4MB for the latter
• Retry publish/fetch on nats.js.errors.NoStreamResponseError
• Error codes are numbers, not strings
• If WPI message fails, report why
• Also reduce WPI interval to 10 seconds, so two have to fail to hit the default 30s window
• Bump nats-py to 2.9.0