added IDLE manager and some updates

[shmish111]

I needed the ability to handle push notifications through the IMAP IDLE command. For this I needed to change the API a little. I also thought that this doesn't need to be tied to gmail so I moved the gmail utilities into a separate namespace. I also bumped the dependencies and added cljfmt. I hope all these changes make sense and I updated the README to take into account all my changes.

• bumped dependencies and added cljfmt
• added ability to listen to push notifications using IDLE command
• removed any gmail specific stuff into a separate namespace
• added more fields and option to choose which ones to message map
• changed store API a little which was needed for idel manager

[owainlewis]

Thanks. This looks great. Happy to merge :+1:

[owainlewis]

Pushed a new release version [io.forward/clojure-mail "1.0.1"]