Improve layout of payment screens to ease navigation

[gtandersen]

Is your feature request related to a problem? Please describe. On the payment screens excessive space is used which makes it difficult to find what you are looking for, especially with regards to sub-accounts:

https://runbox.com/app/account/plans

https://runbox.com/app/account/subscriptions

Describe the solution you'd like The space should be used more efficiently and it should be clearer how to buy sub-accounts, and to see which sub-accounts use which subscriptions.

[gtandersen]

The "Your Subscriptions" page could group subscriptions by main account, sub-accounts, and other add-ons, and chronologically within those groups with the next up for renewal clearly indicated.