Use imap client

[at15]

Due to #1, N1 local sync engine can't work with N1 client now. We can use imap client and download everything and read locally .....

• [ ] fetch email
• [ ] download email
• [ ] download contacts
• [ ] download attachments
• [ ] save info to database
• [ ] provide a simple UI

Ref

• https://imapclient.readthedocs.io/en/stable/ used by N1 sync engine tested on b5344b25997bc3b3a842783bb4fa21738ad5cb64 have encoding problem but works. (SSL is not working though)
• https://github.com/mscdex/node-imap A Node client
• https://github.com/martinrusev/imbox Another python IMAP client which seems have a cleaner API tested on af641553733edd7557245e7cd51985be169d878e SSL is working, but encoding is broke and don't know how to solve it.

[at15]

imbox got problem for encoding, https://github.com/martinrusev/imbox/issues/64

[ghost]

imbox got problem for encoding, martinrusev/imbox#64

This is fixed in current versions (martinrusev/imbox#96)

[at15]

@wagner-certat thanks for letting me know :smile: