Update Vagrant to Ruby 2.4 (#803)

fixes #802

Author: sbrandwoo

Vagrantfile

@@ -7,10 +7,10 @@ Vagrant.configure(2) do |config|
     inline: <<-SHELL
       sudo apt-add-repository ppa:brightbox/ruby-ng
       sudo apt-get update
-      sudo apt-get install -yq ruby2.2 ruby2.2-dev
+      sudo apt-get install -yq ruby2.4 ruby2.4-dev
       sudo apt-get install -yq pkg-config build-essential nodejs git libxml2-dev libxslt-dev
       sudo apt-get autoremove -yq
-      gem2.2 install --no-ri --no-rdoc bundler
+      gem2.4 install --no-ri --no-rdoc bundler
     SHELL
 
   # add the local user git config to the vm