Bump gradle plugin versions

playground/android/app/build.gradle

     resolutionStrategy.eachDependency { DependencyResolveDetails details ->
         def requested = details.requested
         if (requested.group == 'com.android.support') {
-            details.useVersion "26.1.0"
+            details.useVersion "28.0.0"
         }
     }
 }

playground/android/build.gradle

         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.1.3'
+        classpath 'com.android.tools.build:gradle:3.2.1'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

playground/android/gradle.properties

 # org.gradle.parallel=true
 
 android.useDeprecatedNdk=false
-# Disable incremental resource processing as it broke relase build
-# https://github.com/react-community/react-navigation/issues/1976
-# https://developer.android.com/studio/build/gradle-plugin-3-0-0.html
-android.enableAapt2=false

playground/android/gradle/wrapper/gradle-wrapper.properties

 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip