[geary] (14 commits) ...Merge branch 'wip/726281-text-attachment-crlf'. Fixes Bug 726281.

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  4251596... Support in-memory SQLite databases, as well as on-disk data (*)
  743b24d... Make database classes more amenable to asynchronous use. (*)
  587e4e7... Add TestCase.assert_null_string method. (*)
  6f7cff2... Move MidstreamConverter to same source file as other stream (*)
  5c73fbc... Push all ImapDB path management down into to ImapDb.Account (*)
  15d8789... Move attachment related code from ImapDB.Folder to Attachme (*)
  037af00... Improve how attachments are saved to the db and disk. (*)
  a2a9568... Support default content types for both displayed and attach (*)
  bfe665d... Add unit tests for Geary.RFC822.Message body content, fix a (*)
  f1c7976... Ensure we always use the one, same codepath when decoding t (*)
  d91dd36... Update unit tests to ensure text attachments saved without  (*)
  f78939c... Push GResource URL for test data down so it's accessible to (*)
  fe9461e... Add a unit test for upgrading an actual Geary v0.6 database (*)
  440a4d5... Merge branch 'wip/726281-text-attachment-crlf'. Fixes Bug 7

(*) This commit already existed in another branch; no separate mail sent