Fixing the Android Studio detection and making it automatically pick the right builder, good for upgrading Cordova

bin/templates/cordova/Api.js

@@ -343,6 +343,8 @@ Api.prototype.removePlugin = function (plugin, uninstallOptions) {
  */
 Api.prototype.build = function (buildOptions) {
     var self = this;
+    if(this.android_studio)
+      buildOptions.studio = true;
     return require('./lib/check_reqs').run()
     .then(function () {
         return require('./lib/build').run.call(self, buildOptions);

bin/templates/cordova/lib/AndroidStudio.js

@@ -11,7 +11,7 @@ var fs = require('fs');
 var CordovaError = require('cordova-common').CordovaError;
 
 module.exports.isAndroidStudioProject = function isAndroidStudioProject(root) {
-    var eclipseFiles = ['AndroidManifest.xml', 'libs', 'res', 'project.properties', 'platform_www'];
+    var eclipseFiles = ['AndroidManifest.xml', 'libs', 'res'];
     var androidStudioFiles = ['app', 'gradle', 'app/src/main/res'];
 
     // assume it is an AS project and not an Eclipse project