title: Could not find any version that matches com.android.support:support-v7:20.0.+
body: <p>I am new for android development
  I had write </p>
  
  <blockquote>
    <p>classpath 'com.android.tools.build:gradle:1.0.0+'</p>
    
    <p>runproduard() is replaced with minifyenabled. The result : Build successful</p>
  </blockquote>
  
  <p>but at the run time this error occures:</p>
  
  <p>My code is:</p>
  
  <blockquote>
    <p><code>compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:21.0.+'
      compile 'com.android.support:support-v4:21.0.+'</code></p>
  </blockquote>
  
  <p>but 698 warnings as can't find referenced class xom which is added in libs folder</p>
  
  <blockquote>
    <p>Error:Execution failed for task ':app:proguardMobifoodDemoDebug'.
    java.io.IOException: Please correct the above warnings first.</p>
  </blockquote>
  
  <p>My android studio version is 1.0.2 and gradle version is 2.2.1</p>