Implement Bunq API using the bank interface

[RvdK]

Build an Implementation using the bank interface from #42

it should be able to:

• connect to a bunq account
• send money to another account with a customizable comment
• get all incoming transaction from the connected account preferably over a specific time slot

see https://doc.bunq.com/api/1/page/introduction

55 create connection

56 post transaction

57 get transactions

Split into new stories:

85 #86 #87 #88 #89

[RvdK]

not finished yet however everything left is put into smaller stories