Use imaplib2 instead of imaplib

[Acorn-zz]

imaplib2 adds IDLE functionality, and is built on and includes all the functionality of imaplib.

The module is hosted by the author here: http://www.janeelix.com/piers/python/

It could be included as an optional dependency and imported with a try except?

[jaitaiwan]

@joestump not sure why we even have IMAP stuff in this lib...

[joestump]

@jaitaiwan I actually wrote this library because I was accessing IMAP and SMTP over OAuth in Gmail. We should look into this, particularly if it's drop-in.

[jaitaiwan]

Didn't even know that existed. Milestone it maybe?