NanoMQ v0.9.0 Release Note

NanoMQ 0.9.0 changelog:

1. Release newly updated DEB/RPM packages.
2. Refactor sub/unsub logic & topic structure in mqtt_db to get better performance and avoid data racing.
3. New data offline caching mechanism including broker & bridging (new config file).
4. Refactoring HTTP REST APIs to be compatible with EMQX.
5. Remove the CXX compiler requirement in CMakeList.
6. Rule engine now supports parsing JSON payloads.
7. Rule engine supports message persistence with SQLite3.
8. SQL parser supports more commonly used symbols.
9. Optimize webhook & rule to restore performance.
10. Client can send DISCONNECT to clean up its session now.
11. Fix Nanolib's compatibility with GCC under 4.9 https://github.com/emqx/nanomq/issues/634
12. Fix restart cmd is not working
13. Fix data racing of issue https://github.com/emqx/nanomq/issues/666
14. Fix MQTT over Websocket # 668
15. Fix double free of Retain msg https://github.com/emqx/nanomq/issues/689
16. Fix #691 #699 #707