title: Unable to do vagrant up behind proxy
body: <p>I am unable to do a vagrant up (or vagrant add) behind our corporate proxy on a Windows 7 machine.  I have tried with and without http_proxy/https_proxy environment variables.  I tried using the vagrant plugin vagrant-proxyconf with the various http proxy settings but it did not help, the issue isn't with the guest's proxy it is with the host's.  Is there some way to get vagrant itself to use a proxy?</p>
  
  <p>Output from vagrant up:</p>
  
  <pre><code>C:\scratch\vagrant&gt;vagrant up
  Bringing machine 'default' up with 'virtualbox' provider...
  ==&gt; default: Box 'hashicorp/pricise32' could not be found. Attempting to find and install...
  default: Box Provider: virtualbox
  default: Box Version: &gt;= 0
  The box 'hashicorp/pricise32' could not be found or
  could not be accessed in the remote catalog. If this is a private
  box on Vagrant Cloud, please verify you're logged in via
  `vagrant login`. Also, please double-check the name. The expanded
  URL and error message are shown below:
  
  URL: ["https://vagrantcloud.com/hashicorp/pricise32"]
  Error: The requested URL returned error: 404 Not Found
  </code></pre>
  
  <p>Plugins:</p>
  
  <pre><code>C:\scratch&gt;vagrant plugin list
  vagrant-login (1.0.1, system)
  vagrant-proxyconf (1.2.0)
  vagrant-share (1.0.1, system)
  </code></pre>
  
  <p>Vagrant version:</p>
  
  <pre><code>C:\scratch\vagrant&gt;vagrant -v
  Vagrant 1.5.4
  </code></pre>