reset fields when "no" selected on save
fix clearing of other claim details and saving of selection of another claim type
clear work_address fields
more changes to work address clearing
move valid? and save overrides to callbacks
implement validation callbacks.
Fixups

 - Extend validation callbacks to accept conditions
 - Remove validates_address(self). It's not idiomiatic Ruby and is
   superfluous.
 - Remove branching inside reset methods where appropriate
Merge branch 'master' into reset_fields_when_no_selected_on_save

Conflicts:
	app/forms/respondent_form.rb
Merge pull request #273 from ministryofjustice/reset_fields_when_no_selected_on_save

Reset fields when no selected on save