[john] - refactored movement snapshot stats

'active members' is now derived from 'joins' and 'unsubscribes'
[john] - set up dependent: :destroy relationships so that deleting campaigns doesn't create unintentional orphans
[john] - converted hash syntax

Conflicts:
	app/models/email.rb
[john] - updated paranoia gem, made autofire emails and lists paranoid

content modules are never deleted, when they are removed from pages or when objects higher up the heirarchy are destroyed the content module link is removed