1. Persist New User records to Mysql

[johnboy14]

This task relates to the first step in our migration plan for User data. We want to start persisting user data to mysql alongside existing datastores. This task only relates to new user data.

https://docs.google.com/document/d/1pRPeGteUMNblQgkitgh4aLnWPmf0elrs28_545VnMRU/edit

[sanel]

This task also should include proper testing code for validating written data. Without that, we risk to end up with malformed data (validate from mysql point, but invalid comparing to dynamodb content), that will be hard to catch.

[johnboy14]

Good shout. It should be easy to verify through unit testing.