title: Plugin with id 'com.android.library' not found
body: <p>I am receiving this error, when I try to use a library project in Android Studio. The specific line in <code>build.gradle</code> that gives this error is</p>
  
  <pre><code>apply plugin: 'com.android.library'
  </code></pre>
  
  <p>I even tried changing it to</p>
  
  <pre><code>apply plugin: 'android-library'
  </code></pre>
  
  <p>Bu it still doesn't work, instead it says: <code>Error:(7, 0) Plugin with id 'android-library' not found.</code></p>
  
  <p>I even tried to add:</p>
  
  <pre><code>classpath 'com.android.tools.build:gradle:1.2.3.+' 
  </code></pre>
  
  <p>under dependencies in <code>build.gradle</code>, and still nothing...</p>
  
  <p>Any help?</p>
  
  <p>EDIT: The whole build.gradle</p>
  
  <pre><code>    // This buildscript will assemble the MoPub SDK into an AAR.
  
  repositories {
      jcenter()
  }
  
  apply plugin: 'android-library'
  
  group = 'com.mopub'
  
  description = '''MoPub SDK'''
  
  android {
      compileSdkVersion 22
      buildToolsVersion '22.0.1'
  
      defaultConfig {
          versionCode 25
          versionName "3.8.0"
          minSdkVersion 9
          targetSdkVersion 22
          consumerProguardFiles 'proguard.txt'
      }
  
      sourceSets {
          main {
              manifest.srcFile 'AndroidManifest.xml'
              java.srcDirs = ['src/main/java']
              resources.srcDirs = ['src/main/java']
              aidl.srcDirs = ['src/main']
              renderscript.srcDirs = ['src/main']
              res.srcDirs = ['res']
              assets.srcDirs = ['assets']
          }
      }
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), file('proguard.txt')
          }
      }
  
      // Note: You will also need a local.properties file to set the location of the SDK in the same 
      // way that the existing SDK requires, using the sdk.dir property.
      // Alternatively, you can set an environment variable called ANDROID_HOME. There is no 
      // difference between the two methods, you can use the one you prefer.
  }
  
  dependencies {
      classpath 'com.android.tools.build:gradle:1.2.3.+'
      compile 'com.android.support:support-v4:22.0.0'
      compile 'com.android.support:support-annotations:22.0.0'
      compile 'com.mopub.volley:mopub-volley:1.1.0'
  }
  
  // Don't run the Robolectric Unit Tests.
  check.dependsOn.remove("test")
  check.dependsOn.remove("unitTest")
  check.dependsOn.remove("testDebug")
  check.dependsOn.remove("unitTestDebug")
  </code></pre>