Redis migration

This is the code for the redis migration backend.

It takes an old and a new backend, and tries to copy existing keys to the new database before answering anything.
I don't understand this answer. We have two parts in the project:
1. app code: the code that powers Loop when you run it
2. test code: the code that was written to run the tests

If redis_migration.js is part of 1/ it contains a FLUSH DB. This is very bad practice, and since this is only for tests, it should be in 2/