Support Android 9.0 Pie and update buildToolsVersion (#3995)

android/app/build.gradle

 apply from: '../prepare-robolectric.gradle'
 
 android {
-    compileSdkVersion 26
-    buildToolsVersion '26.0.2'
+    compileSdkVersion 27
+    buildToolsVersion '27.0.3'
 
     defaultConfig {
         minSdkVersion 16
-        targetSdkVersion 23
+        targetSdkVersion 27
         versionCode 1
         versionName "1.0"
     }
 dependencies {
     compile fileTree(dir: "libs", include: ["*.jar"])
 
-	compile 'com.android.support:design:25.3.1'
-    compile "com.android.support:appcompat-v7:25.3.1"
+    compile 'com.android.support:design:27.1.1'
+    compile "com.android.support:appcompat-v7:27.1.1"
 
     // node_modules
     compile "com.facebook.react:react-native:+"

android/build.gradle

 buildscript {
     repositories {
         jcenter()
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.2.2'
             // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
             url "$rootDir/../node_modules/react-native/android"
         }
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
-}
+}