Flop deal (#39)

*Refactor deal transformer to take in several contract addresses
* Add flop address to deal transformer

db/migrations/1537814159_add_contract_address_to_deal.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE maker.deal
+  DROP COLUMN contract_address;

db/migrations/1537814159_add_contract_address_to_deal.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE maker.deal
+  ADD COLUMN contract_address VARCHAR;

db/schema.sql

@@ -105,7 +105,8 @@ CREATE TABLE maker.deal (
     header_id integer NOT NULL,
     bid_id numeric NOT NULL,
     tx_idx integer NOT NULL,
-    raw_log jsonb
+    raw_log jsonb,
+    contract_address character varying
 );