fix regression - deployment fails when -u is not specified

ChangeLog

@@ -1,3 +1,6 @@
+0.5.4 -
+	* fix deploy failure when no url is specified
+
 0.5.3 -
 	* fix race in library function git.currentSHA - wait for "close": #98
 

awsbox.js

@@ -381,10 +381,14 @@ verbs['create'] = function(args) {
           checkErr((opts.d && err) ? 'updating DNS: ' + err.msg : null);
 
           console.log("   ... Instance ready, setting human readable name in aws");
-          vm.setTags(r.instanceId, {
-            Name: longName,
-            InitialDNS: dnsHost
-          }, function(err) {
+
+          // set some tags at creation (VM name included)
+          var tagSet = {
+            Name: longName
+          };
+          if (dnsHost) tagSet.InitialDNS = dnsHost;
+
+          vm.setTags(r.instanceId, tagSet, function(err) {
             checkErr(err);
             console.log("   ... name set, waiting for ssh access and configuring");
             var config = { public_url: (opts.u || "http://" + deets.ipAddress) };