Fixes:
- Fix B64 encoding of Bitmaps
- Figure out how to highlight email backgrounds when selected in list
- Refine view email page
-- Delete/read/unread/move actions that don't break everything
- Improve network status page
-- Show full network error? Make it copy-able?

Tasks:
- Subclass EmailListFragment for each default mailbox
- Refactor code
-- Reorganize for clarity
-- Optimize use of Android lifecycles

Features:
- Show check mail status in inbox list header
- Pull-to-check
- Import/export identities
-- Export Destination / make it copyable
- Show contact pictures in recipients dropdown
- Add optional CC: and BCC: fields
- "Empty trash" option in Trash folder