title: Homestead.yaml *Shell provisioner `args` must be a string or an array
body: <p>I was editing my homestead.yaml file and I am certain the indentation is correct -- I however get this following error:</p>
  
  <pre><code>Bringing machine 'default' up with 'virtualbox' provider...
  There are errors in the configuration of this machine. Please fix
  the following errors and try again:
  
  shell provisioner:
  * Shell provisioner `args` must be a string or array.
  * Shell provisioner `args` must be a string or array.
  * Shell provisioner `args` must be a string or array.
  * Shell provisioner `args` must be a string or array.
  </code></pre>
  
  <p>My homestead.yaml file:</p>
  
  <pre><code>---
  ip: "192.168.10.10"
  memory: 2048
  cpus: 1
  
  authorize: ~/.ssh/id_rsa.pub
  
  keys:
       - ~/.ssh/id_rsa
  
  folders: 
       - map: ~/Sites
         to: /home/vagrant/Sites
  
  sites: 
       - map: scheduleify.dev
         to: /home/vagrant/Sites/scheduleify/public
  
       - map: phpmyadmin.dev
         to: /home/vagrant/Sites/phpmyadmin
  
       - map: articles.dev
         to: /home/vagrant/Sites/learning-laravel5    
  
  databases:
       - scheduleify
  
  variables:
      - key: APP_ENV
    - value: local
  </code></pre>
  
  <p>Any ideas on what is wrong with the file? </p>