Pull trade offer ID directly from listing page

index.js

@@ -10,6 +10,12 @@ require('util').inherits(SteamCommunity, require('events').EventEmitter);
 module.exports = SteamCommunity;
 
 SteamCommunity.SteamID = SteamID;
+SteamCommunity.ConfirmationType = {
+	// 1 is unknown, possibly "Invalid"
+	"Trade": 2,
+	"MarketListing": 3
+	// 4 is opt-out or other like account confirmation?
+};
 
 function SteamCommunity(options) {
 	options = options || {};