MFA support

[Luke-Williams9]

This module is great, but many of us use cloud-hosted CWC and require MFA support. I've added that into my fork, plus a few other small changes (better epoch time handling, centralizing a couple variables, etc)

This is my first pull request... Please forgive me if I'm doing something wrong. I'd like to submit only the MFA changes, but I'm not sure how to include/exclude specific changes yet.