Added manifest

Assets/Plugins/Android/AndroidManifest.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest
+        xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:tools="http://schemas.android.com/tools">
+
+    <!-- Permission to use Google Play Billing -->
+    <uses-permission android:name="com.android.vending.BILLING" />
+
+    <application>
+        <activity android:name="com.unity3d.player.UnityPlayerActivity"
+                  android:theme="@style/UnityThemeSelector">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+            <meta-data android:name="unityplayer.UnityActivity" android:value="true" />
+        </activity>
+    </application>
+</manifest>

Assets/Plugins/Android/AndroidManifest.xml.meta

@@ -0,0 +1,7 @@
+fileFormatVersion: 2
+guid: dfa0c188589fdd44680f8b6fc785b055
+TextScriptImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

ProjectSettings/ProjectSettings.asset

@@ -253,7 +253,7 @@ PlayerSettings:
   clonedFromGUID: 00000000000000000000000000000000
   templatePackageId: 
   templateDefaultScene: 
-  useCustomMainManifest: 0
+  useCustomMainManifest: 1
   useCustomLauncherManifest: 0
   useCustomMainGradleTemplate: 1
   useCustomLauncherGradleManifest: 0