Updated Requests

- added Date and Account field to Saved Requests
- requests are now saved as dict()
  old requests will be deleted!!
- Account field is hidden when only 1 account is available
- address line now follows the current_account
- saved requests is sortable, default sorted by date
- saved requests only shows request for current_account
Merge branch 'contacts' of github.com:Tafelpoot/electrum into Tafelpoot-contacts
various fixes for reveive_requests
Merge branch 'Tafelpoot-contacts'