Squashed commit of the following:

    tests email changes on account

    fix cucumbers for account udate callback issues

    removes redundant bills modal form

    fix removal of visible_to knock ons

    update models to remove include visible

    refactor categories controller to use current_account as parent

    refactor bills controller to use current_account as parent

    refactor customers controller to use current_account as parent and not use visible

    fix spec for accounts controller to stub Stripe

    changes email on Stripe and account when user changes email

    change pdf to A4 size

    adds cancel view

    remove validation on account email except on create

    adds stripe columns to account and updates through process_sale

    adds card and next invoice detail to account from Stripe

    add check for 0 plan on show helpers

    add buttons to account show for change of card, cancel and bill history

    adds cancel subscription to account

    refactoring account create process