add transfer operation

lib/broadcast.js

@@ -118,5 +118,22 @@ module.exports = {
 		this.comment(username, password, body.substr(0, 30), body, null, parent_author, parent_permlink, function(e,r) {
 			cb(e,r);
 		})
+	},
+	transfer: function(username, password, to, amount, asset, memo, cb) {
+		if (amount.toFixed(3) <= 0) cb('Cannot transfer a negative amount (aka: stealing)');
+		if (asset != 'SBD' && asset != 'STEEM') cb('Wrong asset. Must be STEEM or SBD');
+		var tx = {
+			extensions: [],
+			operations: [['transfer', {
+				from: username,
+				to: to,
+				amount: formatter.amount(amount, asset),
+				memo: memo
+			}]]
+		};
+		var privKeys = steemAuth.getPrivateKeys(username, password, ['active']);
+		this.send(username, password, tx, privKeys, function(err, result) {
+			cb(err, result);
+		})
 	}
 };

lib/formatter.js

@@ -35,5 +35,9 @@ module.exports = {
 			return permlink;
 		}
 		else return this.sanitizePermlink(title)
+	},
+	amount: function(amount, asset) {
+		// maybe improve this
+		return amount.toFixed(3) + ' ' + asset;
 	}
 };