Closes GH-721 Set default host header properly

However, this test is failing for some quite unrelated issue.
Getting some odd "socket hangup" crashes, and only the first request
ever makes it to the server.

lib/https.js

@@ -54,6 +54,9 @@ function Agent(options) {
 inherits(Agent, http.Agent);
 
 
+Agent.prototype.defaultPort = 443;
+
+
 Agent.prototype._getConnection = function(host, port, cb) {
   var s = tls.connect(port, host, this.options, function() {
     // do other checks here?