Annual subscription#9

Description
When I sign up for an annual subscription
I want to get a discount
So I can get a discount by paying in advance.

Current behaviour
No way to pay for an annual plan

Expected behaviour
A way to select annual or monthly plan, annual plan would come with an 15% discount.

Now available via the billing screen for 10 users.
https://billing.stripe.com/p/login/3cs5n86dL3sKeaI000