title: Could not find adb Please set the ANDROID_HOME environment variable with the Android SDK root directory path
body: <p>I am getting the below error message:</p>
  
  <pre><code>An unknown server-side error occurred while processing the command. 
  Original error: Could not find adb Please set the ANDROID_HOME 
  environment variable with the Android SDK root directory path. 
  (Selenium::WebDriver::Error::UnknownError)
  </code></pre>
  
  <p>I have setup all the below:</p>
  
  <pre><code>info AppiumDoctor Appium Doctor v.1.4.2
  info AppiumDoctor ### Diagnostic starting ###
  info AppiumDoctor  ✔ The Node.js binary was found 
  at:/usr/local/bin/node
  info AppiumDoctor  ✔ Node version is 7.10.0
  info AppiumDoctor  ✔ ANDROID_HOME is set to: 
  /Users/shafiq.malik/Library/Android/sdk
  info AppiumDoctor  ✔ JAVA_HOME is set to: /Library/Java/Home
  info AppiumDoctor  ✔ adb exists at: 
  /Users/shafiq.malik/Library/Android/sdk/platform-tools/adb
  info AppiumDoctor  ✔ android exists at: 
  /Users/shafiq.malik/Library/Android/sdk/tools/android
  info AppiumDoctor  ✔ emulator exists at: 
  /Users/shafiq.malik/Library/Android/sdk/tools/emulator
  info AppiumDoctor  ✔ Bin directory of $JAVA_HOME is set
  info AppiumDoctor ### Diagnostic completed, no fix needed. ###
  info AppiumDoctor
  info AppiumDoctor Everything looks good, bye!
  info AppiumDoctor
  </code></pre>
  
  <p>I am not sure what I am missing. Can somebody please advise?</p>