title: Android sdk is missing, out of date or corrupted (SDK tools directory is missing)
body: <p>I have installed android studio 3.0.1 in new PC.
  when i open android studio, a message say :<a href="https://i.stack.imgur.com/2rJHI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2rJHI.png" alt="enter image description here"></a></p>
  
  <p>also when i want to download sdk it shows like this  :<a href="https://i.stack.imgur.com/agqAl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/agqAl.png" alt="enter image description here"></a></p>