Detect another type of "Sent Mail" folder
Detect another type of "Sent Mail" folder

Summary: We weren't detecting folders named "INBOX.Sent" as sent folders. This diff fixes this, as well as some pep8 issues.

Test Plan: Tested by running a full sync of a fastmail account. Note that fastmail accounts shouldn't be affected by this change, though.

Reviewers: emfree

Reviewed By: emfree

Projects: #sync-engine

Differential Revision: https://phab.nylas.com/D2047

closeio/nylas,jobscore/sync-engine,nylas/sync-engine,nylas/sync-engine,nylas/sync-engine,nylas/sync-engine,jobscore/sync-engine,closeio/nylas,closeio/nylas,closeio/nylas,jobscore/sync-engine,jobscore/sync-engine