autoprovider, buildQt not builds only necessery files, fixed gulpfile

lib/main.js

@@ -387,6 +387,10 @@ web3.setProvider = function(provider) {
     web3.provider.sendQueued();
 };
 
+web3.haveProvider = function() {
+    return !!web3.provider.provider;
+};
+
 var Filter = function(options, impl) {
     this.impl = impl;
     this.callbacks = [];