title: buildToolsVersion not specified
body: <p>I am getting an error "Project Refresh Failed. Cause: buildToolsVersion not specified"
  Here is my app\build.gradle file</p>
  
  <pre><code>apply plugin:'com.android.application'
  
  android {
      compileSdkVersion 26
      buildToolsVersion "26.0.3"
      defaultConfig {
          applicationId "edu.cmu.sphinx.pocketsphinx"
          minSdkVersion 14
          targetSdkVersion 26
          versionCode 1
          versionName "1"
      }
  }
  
  dependencies {
      compile project(':aars')
      compile project(':models')
      compile 'com.android.support:appcompat-v7:26.1.0'
  }
  </code></pre>
  
  <p>Here is my project gradle file</p>
  
  <pre><code>buildscript {
      repositories {
          jcenter()
          maven { url 'https://maven.google.com' }
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:2.3.1'
      }
  }
  
  allprojects {
      repositories {
          jcenter()
          maven { url 'https://maven.google.com' }
      }
  }
  </code></pre>
  
  <p>Any help please?</p>