title: Jar files in libs folder are not used in Android Gradle build
body: <p>i just started to play with the gradle build system for Android.</p>
  
  <p>However i'm not able build one of my projects. It depends on a jar in the libs/ folder.</p>
  
  <p>Doing <code>gradle build</code> fails in the <code>compileDebug</code> task because all of the classes from the jar file are missing.</p>
  
  <p>It is a library project! Here is my build.gradle file:</p>
  
  <pre><code>buildscript {
      repositories {
          mavenCentral()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:0.2'
      }
  }
  
  apply plugin: 'android-library'
  
  android {
      target='android-16'
      sourceSets {
          main {
              manifest {
                  srcFile 'AndroidManifest.xml'
              }
              java {
                  srcDir 'src'
              }
              res {
                  srcDir 'res'
              }
              assets {
                  srcDir 'assets'
              }
              resources {
                  srcDir 'src'
              }
          }
      }
  }
  </code></pre>
  
  <p>Am i missing something obvious?</p>
  
  <p>Goddchen</p>