Release 1.20.0-incubating

This is the second of Apache Pulsar since entering the ASF incubator.

Major changes in this release include:

• [#620] [#717] [#718] Reader API support for C++ , Python & Websocket Proxy
• [#634] Added Message dispatch throttling
• [#731] Added End to End Encryption
• [#732] Support for Event Time for messages
• [#751] Guaranteed Deduplication of Messages
• [#761] Kafka API wrapper for Pulsar client library

Complete list of changes can be found at:
https://github.com/apache/incubator-pulsar/milestone/9?closed=1