PayPal sidebar integration

NOTE: Paypal Subscription isn't available in every country for private clients

To setup the Coffee Donation/Subscription feature:

1. Login to paypal.com

2. Go to Merchant Services and create a new subscription button (if personal account create a normal button with 3 options), any name is fine.

3. Setup the 3 options to match the defaults (if you want others you will need to edit your pod code)

None of the other defaults need to be tweaked, so save your button and add the button ID to your diaspora.yml by following the example in diaspora.yml.example