5.2.1 release

5.2.1 release 

Improvements 

• Improvements to the automatic restart logic of Connectors
• Support Broker JMX configurations from the latest Confluent releases
• Allow to change the Kafka cluster associated with a Lenses installation (a Lenses database reset might still be the best option)

Fixes 

• Fix ACLs link in the Overview section of the Admin page
• In the Explore Topic screen, the Records limit field does not show new values

Other 

• Switch Lenses and SQL Processors base docker images to Ubuntu