title: Error:Cause: buildToolsVersion is not specified
body: <p>I create a simple project and then I right-click on the project and then I use the <code>make mudole app</code> option. Now I have two <code>build.gradle</code> folders: 1- <code>build.gradle:project My Application</code>. 2- <code>build.gradle: Mudole app</code>. the first <code>build.gradle</code> is as follows:</p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  apply plugin: 'com.android.library'
  buildscript {
      repositories {
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:1.3.0'
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          jcenter()
      }
  }
  </code></pre>
  
  <p>And the second <code>Build.gradle</code> folder is as follows:</p>
  
  <pre><code> apply plugin: 'com.android.application'
  android {
      compileSdkVersion 23
      buildToolsVersion "23.0.0"
  
      defaultConfig {
          applicationId "com.exam.exam.myapplication"
          minSdkVersion 7
          targetSdkVersion 23
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
  }
  </code></pre>
  
  <p>And now I click on the <code>run</code> option to create <code>aar</code> file from this project But I get the following error:</p>
  
  <pre><code>Error:Cause: buildToolsVersion is not specified.
  </code></pre>