This involves redoing the persistence model, to split general,
account, and folder settings into separate SharedPreference stores.
It also requires some preferences to be moved into UnifiedEmail.
Depends on Ibe2e3f93ec164370535ffc5f5b2409544cc8d36d (UnifiedEmail)
Change-Id: Ie6ec389b5b5d2e7ab1b299d0877811ae716526e2
* Restore Imap1 code
* Legacy users will use Imap1
* Existing Imap2 users will continue to use Imap2
* New accounts will be created in Imap1
* More to follow
Bug: 7203993
Change-Id: I8b86fcada59a854fd464d5269c94d00ebae85459