title: No Gradle "build" task despite build.gradle applying plugin com.android.application
body: <p>Somehow I don't have a <code>build</code> task:</p>
  
  <pre><code>$ ./gradlew tasks --all
  :tasks
  
  ------------------------------------------------------------
  All tasks runnable from root project
  ------------------------------------------------------------
  
  Build Setup tasks
  -----------------
  init - Initializes a new Gradle build. [incubating] [wrapper]
  wrapper - Generates Gradle wrapper files. [incubating]
  
  Help tasks
  ----------
  components - Displays the components produced by root project 'apps-android-commons'. [incubating]
  dependencies - Displays all dependencies declared in root project 'apps-android-commons'.
  dependencyInsight - Displays the insight into a specific dependency in root project 'apps-android-commons'.
  help - Displays a help message.
  model - Displays the configuration model of root project 'apps-android-commons'. [incubating]
  projects - Displays the sub-projects of root project 'apps-android-commons'.
  properties - Displays the properties of root project 'apps-android-commons'.
  tasks - Displays the tasks runnable from root project 'apps-android-commons'.
  
  BUILD SUCCESSFUL
  </code></pre>
  
  <p>Despite my <code>commons/app/build.gradle</code> that applies (as described <a href="https://stackoverflow.com/questions/21396777/how-do-i-add-a-task-to-main-build-task-in-gradle">in this other QA</a>) a relevant plugin:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  dependencies {
      compile fileTree(include: '*.jar', dir: 'libs')
      compile 'fr.avianey.com.viewpagerindicator:library:2.4.1.1@aar'
      compile 'in.yuvi:http.fluent:1.3'
      compile 'com.android.volley:volley:1.0.0'
      compile 'com.nostra13.universalimageloader:universal-image-loader:1.8.4'
      compile 'ch.acra:acra:4.5.0'
      compile 'org.mediawiki:api:1.3'
      compile 'commons-codec:commons-codec:1.10'
      compile 'com.android.support:support-v4:23.4.0'
      compile 'com.android.support:appcompat-v7:23.4.0'
      compile 'com.android.support:design:23.4.0'
  
      //noinspection GradleDependency - old version has required feature
      compile 'com.google.code.gson:gson:1.4'
  }
  
  android {
      compileSdkVersion 23
      buildToolsVersion "23.0.3"
  
      useLibrary  'org.apache.http.legacy'
  
      defaultConfig {
          applicationId "fr.free.nrw.commons"
          minSdkVersion 11
          targetSdkVersion 23
  
          ndk {
              moduleName "libtranscode"
          }
      }
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
          }
      }
  
      lintOptions {
          disable 'MissingTranslation'
          disable 'ExtraTranslation'
      }
  }
  </code></pre>
  
  <p><strong>QUESTION:</strong> Why is that, am I doing something wrong?</p>
  
  <p>Here is my project structure:</p>
  
  <pre><code>ROOT
   /commons
     /app
  </code></pre>
  
  <p>... and I execute <code>./gradlew</code> in ROOT.</p>