fix(connection): use connectPolicy not this.policy.connect

The most recent refactor for SASL properly extracted the connect
policy provided to the AMQPClient, and modified that value when
making decisions about the chosen SASL strategy. The codebase
previously had modified the passed in policy directly (incorrectly)
leading to invalid values being used for the initial open frame
sent out.

lib/amqp_client.js

@@ -132,7 +132,7 @@ AMQPClient.prototype.connect = function(url, policyOverrides) {
       connectPolicy.options.hostname = address.vhost;
     }
 
-    self._connection = self._newConnection();
+    self._connection = self._newConnection(connectPolicy);
     self._connection.on(Connection.Connected, function(c) {
       debug('connected');
       self.emit(AMQPClient.ConnectionOpened);
@@ -359,9 +359,9 @@ AMQPClient.prototype._clearConnectionState = function(saveReconnectDetails) {
 };
 
 // Helper methods for mocking in tests.
-AMQPClient.prototype._newConnection = function() {
+AMQPClient.prototype._newConnection = function(connectPolicy) {
   var self = this;
-  var connection = new Connection(this.policy.connect);
+  var connection = new Connection(connectPolicy);
   connection.on(Connection.ErrorReceived, function(e) {
     debug('connection error: ', e);
     self.emit(AMQPClient.ErrorReceived, e);