message: Modify exchange.abi to match types in exchange.hpp.
diff: "name": "order_id",
  "fields": {
  "name" : "account_name",
  - "id" : "uint64"
  + "number" : "uint64"
  }
  },{
  "name" : "bid",
  }
  ],
  "actions": [{
  - "action": "buy",
  + "action_name": "buy",
  "type": "buy_order"
  },{
  - "action": "sell",
  + "action_name": "sell",
  "type": "sell_order"
  },{
  - "action": "cancelbuy",
  + "action_name": "cancelbuy",
  "type": "order_id"
  },{
  - "action": "cancelsell",
  + "action_name": "cancelsell",
  "type": "order_id"
  }
  ],
  - "tables": [
  - {"table":"bids","type":"bid"},
  - {"table":"asks","type":"ask"},
  - {"table":"account","type":"account"}
  + "tables": [{
  + "table_name": "bid",
  + "index_type": "i128i128",
  + "key_names": [
  + "buyer",
  + "at_price"
  + ],
  + "key_types": [
  + "order_id",
  + "price"
  + ],
  + "type": "bid"
  + },{
  + "table_name": "ask",
  + "index_type": "i128i128",
  + "key_names": [
  + "seller",
  + "at_price"
  + ],
  + "key_types": [
  + "order_id",
  + "price"
  + ],
  + "type": "ask"
  + },{
  + "table_name": "account",
  + "index_type": "i64",
  + "key_names": [
  + "owner"
  + ],
  + "key_types": [
  + "account_name"
  + ],
  + "type": "account"
  + }
  ]
  }
  