Align all Apps to the latest 2.1.2.BUILD-SNAPSHOT parent pom

[tzolov]

Currently many apps such as aggregator, cdc-debezium, syslog, splitter, scriptable-transform, tensorflow, redis, python, pmml and more ... are still at the old parent pom BS version (e.g. 2.1.1.BUILD-SNAPSHOT).

• Those need to be migrated to the latest parent 2.1.2.BUILD-SNAPSHOT.
• Also update apps' own version to match this of the parent.
• Update the Darwin-BUILD-SNAPSHOT-stream-applications-kafka-maven and Darwin-BUILD-SNAPSHOT-stream-applications-kafka-docker

Affected apps:

• [ ] aggregator
• [ ] cdc-debezium
• [ ] syslog
• [ ] splitter
• [ ] scriptable-transform
• [ ] tensorflow
• [ ] redis
• [ ] python
• [ ] pmml

TODO: Find and list the other affected apps

[sobychacko]

@tzolov all the app starters' parent is now updated to 2.1.2.BUILD-SNAPSHOT. Why do we need to update the app's versions? I think they should be left where they are now as they were updated to snapshots from their respective last releases.