separate templates for New Billing Account and Manage Accounts
separate template for New/Edit Subscription
refactoring views
page_name to page_title
create account in form's method
update account in form
refactor creating and modifying a subscription
refactor adjust_credit
move adjust_credit to CreditForm
refactor CreditLine.adjust_credit
refactor EditSubscriptionView.page_context
remove unused context variable
allow negative adjustments to CreditLines