title: The extension manifest is invalid, CompositeC1WebFormExtensions.vsix
body: <p>I just downloaded the CompositeC1WebFormExtensions.vsix from the official composite CMS C1 documentation website and I'm getting an error when trying to install this.</p>
  
  <p>I'm on Windows 8 using Visual Studio 2010 pro</p>
  
  <p>CompositeC1WebFormExtensions.vsix</p>
  
  <p>Has anyone been able to successfully install this extension?</p>
  
  <p>Thanks</p>
  
  <p>David</p>