Added a new DAO function which archives SMS senders by setting
archived to True. This raises an ArchiveValidationError, if
trying to archive a default SMS sender or an inbound number.
Added a new endpoint for archiving SMS senders.
Updated the DAO methods which return a single SMS sender and all SMS senders
to only return the non-archived senders. Changed the error raised in the Admin
interface from a SQLAlchemyError to a BadRequestError.
Added a new boolean column, `archived`, with a default of False to the
three models which are used to specify the 'reply to' address for
notifications:
* ServiceEmailReplyTo
* ServiceSmsSender
* ServiceLetterContact
Refactor tests/db/create_service() to behave more like the real world.
Created new create_service_with_inbound_number and create_service_with_defined_sms_sender() test/db methods.
When a service is allocated an inbound number and they only have one SMS sender, then update that SMS sender to the inbound number.
That way they will not have more than one SMS sender and will not have to choose to use either one.
