Change install_node.sh to install npm 3 instead. Default RAM for vagrant box is now 4 GB. (#7478)

Vagrantfile.example

@@ -6,7 +6,7 @@ VAGRANTFILE_API_VERSION = "2"
 
 Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
   config.vm.provider "virtualbox" do |v|
-    v.memory = 768
+    v.memory = 4096
     v.cpus = 1
     v.customize ["setextradata", :id, "VBoxInternal2/SharedFoldersEnableSymlinksCreate/vagrant", "1"]
   end

vagrant_scripts/install_node.sh

@@ -16,7 +16,7 @@ nvm use
 nvm alias default current
 
 echo Update npm...
-npm install -g npm@2
+npm install -g npm@3
 
 echo Installing global modules...
 npm install -g gulp bower grunt-cli mocha