Added google() to allprojects to root build.gradle

Fixes issue with jcenter not always resolving google dependencies

Author: jkasten2

OneSignalSDK/build.gradle

@@ -2,8 +2,8 @@
 
 buildscript {
     repositories {
-        jcenter()
         google()
+        jcenter()
         maven { url 'https://maven.google.com' }
         // OneSignal-Gradle-Plugin - Local testing
 //      maven { url uri('../../repo') }
@@ -23,6 +23,7 @@ buildscript {
 
 allprojects {
     repositories {
+        google()
         jcenter()
         flatDir {
             dirs 'libs'