title: AAR is missing my dependencies
body: <p>I have created a new project with only a module that is a library.</p>
  
  <p><img src="https://i.stack.imgur.com/BeAtl.png" alt="android studio"></p>
  
  <p>And here is my build.gradle</p>
  
  <pre><code>apply plugin: 'com.android.library'
  
  android {
      compileSdkVersion 21
      buildToolsVersion "21.1.2"
  
      defaultConfig {
          minSdkVersion 18
          targetSdkVersion 21
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 
               'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:21.0.3'
      compile 'org.altbeacon:android-beacon-library:2+@aar'
  }
  </code></pre>
  
  <p>If I build this project, it generates an <code>aar</code> file called <code>app-debug.aar</code> with 45kb. I was wondering why I need to include all dependencies on main project because if I include only the dependency of <code>app-debug.aar</code>, it throws a <code>ClassNotFoundException</code>.</p>
  
  <p>Why I need to do this?</p>
  
  <pre><code>dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:21.0.3'
      compile ('org.altbeacon:android-beacon-library:2+@aar')
      compile (name:'app-debug', ext:'aar')
  }
  </code></pre>
  
  <p>Can I find a way that I don't need to include dependencies like altbeacon on main project (apk) and work only with <code>app-debug.aar</code> dependency?</p>
  
  <p>Thanks in advance.</p>