Store Signature Data
---------------------

CREATE TABLE mobile_return_signature
(
  id serial NOT NULL,
  mobile_return_id integer NOT NULL,
  signature bytea,
  lat numeric(20,17),
  lng numeric(20,17),
  signature_time bigint,
  CONSTRAINT mobile_return_dignature_pk PRIMARY KEY (id),
  CONSTRAINT mobile_return_signature_mobile_return_fk FOREIGN KEY (mobile_return_id)
      REFERENCES mobile_return (id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION
)