Twelve: Add android.intent.category.DEFAULT to main intent filter

This seems to be necessary to be available for
android.intent.category.APP_MUSIC intents.

Change-Id: I9cf797fcf10270e23d86b57ca3eba1cd62726918
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 8448e34..d76520e 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -37,6 +37,7 @@
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
+                <category android:name="android.intent.category.DEFAULT" />
                 <category android:name="android.intent.category.LAUNCHER" />
                 <category android:name="android.intent.category.APP_MUSIC" />
             </intent-filter>