Enable use of fullwidth main content section depending on presence of stripe_pk.
Add add_payment_details page and form.
Use a partial for the credit card details form.
Add update payment details template and view function.
Remove payment info from account_details page.
Display add/update links based on if we already have payment details saved.
Change payment form submit button text.
Remove old stripe test code.
Create/retrieve customer and update stripe_customer_id on account.
Add management task for charging active accounts once and only once during the current month.
Add management task to manually charge and activate an account.
Handle user attempts to access inactive account.
Merge pull request #4 from buildingspeak/master-stripePayments-shane

Add user management of payment details, management tasks for a) charging all active accounts and b) manually charging any amount to any account