Update for Android Studio 3.1

app/build.gradle

@@ -1,11 +1,7 @@
-import com.android.builder.model.ProductFlavor
-import org.apache.tools.ant.taskdefs.condition.Os
-
 apply plugin: 'com.android.application'
 
 android {
     compileSdkVersion 27
-    buildToolsVersion '27.0.3'
 
     defaultConfig {
         minSdkVersion 16

build.gradle

@@ -2,6 +2,7 @@
 buildscript {
     repositories {
         jcenter()
+        google()
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:3.0.1'
@@ -11,5 +12,6 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        google()
     }
 }