Show paypal email on account page

This aims to solve #2388. 

Do we want to allow people to have both a valid bank account **and** PayPal configured? If not, the bank account row could be hidden for people with PayPal. 

Also, should we let people remove their paypal email themselves? We're unsure about adding on #2387, but nothing was said about removal. In fact, we had  a support request recently where a user wanted his PayPal email removed.