Fixes:
- Hide old password field in SetPasswordFragment if none is set
- Don't show Share menu for new contacts
- Fix tick over selected emails
- 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:
- Add a "do you want to skip tutorial" dialog to back button
- More layouts for intro and setup (tune for each screen size)
- Create and bundle better network status icons
- Subclass EmailListFragment for each default mailbox
- Refactor code
-- Reorganize for clarity
-- Optimize use of Android lifecycles

Features:
- Fingerprints for identities and contacts
  - Easy way for users to compare to validate
- Public address book lookup
- Add optional CC: and BCC: fields
- Forward
- Reply all
- Attachments
- QR codes for identities
- "Empty trash" option in Trash folder
- Overlay to explain