Added Redis backup and restore capabilities

Currently limited to rdb and doesn't muck with config files.
Refactored large portions of MySQL backup code to share whatever
the two datastores had in common.
I totally forgot about this. I figured I'd generate these constants using this: https://github.com/TimSimpsonR/sneaky-pete/blob/master/generate_code.py

Now I'm feeling lazy and don't want to but I guess it wouldn't take much work to generate these.