Installer: VirtualBox and JDK key in requirements.json should not contain version

"jdk8.zip": {
    "bundle": "yes",
    "url": "http://cdn.azul.com/zulu/bin/zulu8.13.0.5-jdk8.0.72-win_x64.zip"
  },
  "vagrant.msi": {
    "bundle": "no",
    "url": "https://releases.hashicorp.com/vagrant/1.7.4/vagrant_1.7.4.msi"
  },
  "VirtualBox-5.0.8.exe": {
    "bundle": "no",
    "version": "5.0.8",
    "revision": "103449",
    "url": "http://download.virtualbox.org/virtualbox/5.0.8/VirtualBox-5.0.8-103449-Win.exe"
  }