title: Android Studio 3.0: buildToolsVersion not found in gradle files
body: <p>I recently installed new stable version of Android Studio (v3.0). Then created a new project and there was not any problem. But saw there is no <code>buildToolsVersion</code> field in the app-level <code>build.gradle</code> file.  Even I searched all project files (<kbd>Ctrl</kbd><kbd>Shift</kbd><kbd>F</kbd>), but didn't find anything!</p>
  
  <p><strong>What does this mean?</strong> And how can I determine what is the version of Build Tools in my app module?</p>
  
  <hr>
  
  <p><strong>build.gradle (Project):</strong></p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
  
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.0.0'
  
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p><strong>build.gradle (Module: app):</strong></p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 26
      defaultConfig {
          applicationId "ir.e900.androidstudio30"
          minSdkVersion 15
          targetSdkVersion 26
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation 'com.android.support:appcompat-v7:26.1.0'
      implementation 'com.android.support.constraint:constraint-layout:1.0.2'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.1'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
  }
  </code></pre>