title: NuGet for solutions with multiple projects
body: <p>Suppose I have a solution with 3 projects:</p>
  
  <ul>
  <li>Core</li>
  <li>UI</li>
  <li>Tests</li>
  </ul>
  
  <p>Some of the NuGet packages I use will apply to all 3 projects. Some will just apply to UI and Tests, and some will just apply to Tests (like NUnit).</p>
  
  <p>What is the <strong>right</strong> way to set this up using NuGet? </p>
  
  <ol>
  <li>Should I use "Add Library Package Reference" on all three projects any time I need a reference? </li>
  <li>Should I use "Add Library Package Reference" the first time I need a package, and then use Add Reference->Browse for subsequent usages?</li>
  </ol>
  
  <p>In either case, how many <em>packages.config</em> files should I have?</p>