Upgrade gradle version

example/android/build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.2.2'
+        classpath 'com.android.tools.build:gradle:2.3.3'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

example/android/gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Thu Sep 15 09:59:50 IDT 2016
+#Fri Jun 30 16:12:20 EDT 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip