title: gradle sync Error "cvc-complex-type.2.4.a:"
body: <p>I have installed the latest android studio and I try to sync an old project that I download from GitHub and I get this Error:</p>
  <pre><code>cvc-complex-type.2.4.a: Invalid content was found starting with element 'base-extension'. One of '{codename, tag}' is expected.
  </code></pre>
  <p>and This</p>
  <pre><code>CVC-complex-type.2.4.d: Invalid content was found starting with element 'base-extension'. No child element is expected at this point.
  </code></pre>