title: Running a powershell script BeforeBuild to modify web.config - how?
body: <p>I have a standard C# MVC web project with a <code>web.config</code>.  What I'd like to do (please don't dig into the intentions here - it's a long story) - is run a powershell script (or executable, less preferably) to modify the contents of the web.config before building.  </p>
  
  <p>I've noticed the <code>BeforeBuild</code> section of my csproj file, but I don't know how to leverage this to run a script against my web.config.  Is this possible?</p>