[TASK] update endpoints

- post payment: POST `/v1/accounts{address}/payments`
- get new wallet: GET `/v1/wallet/new`
- remove `/v1/tx` and `/v1/transaction` in favor of `/v1/transactions`
- move wallet api from `accounts.js` to `wallet.js`
- update tests
Merge pull request #177 from geertweening/develop

[TASK] update endpoints