Fix Issue #991: RTL SASS Stylesheet 

Conflicts:
	app/controllers/users_controller.rb
	config/locales/diaspora/en.yml
	db/schema.rb
	spec/controllers/users_controller_spec.rb
	spec/mailers/notifier_spec.rb

Fix for issue #1600: Missing string for translation ("Recent notifications")

This reverts commit a6f2f82c.

fixed emails to show avatars, have subject lines that allow threading in email clients, and relevant content previews

Update of Galician (gl) translation

Had forgotten to use the right string delimiters (not needed, but hey, I want to do things right\!).

Use activerecord-import in ReceiveLocalBatch.  The default behavior of it is to do an On Duplicate Key Update updated_at = Time.now, but we have a test for that case anyway.

Vanna doesn't include helpers so we have to include them in views separately to use them. The absence of  this line was producing a deprecation warning for error_messages_for, because our helper redefines that method (it was removed from rails).