Have a way to live reimport / update matrix settings

[brendanheywood]

Roughly:

1. In prod matrix you would setup the new settings you want to take effect
2. In the other environment have a 'test reimport' which pings a custom web service in production
3. prod only returns values for that env and only matrix values, never real values
4. it encrypts it using the shared secret
5. The other env decrypts and then sets it all
6. Takes you to the config log page to see exactly what it just set

The main purpose of this is to make the matrix update -> test cycle as fast as possible