fix launcher icon references

AndroidManifest.xml

@@ -57,7 +57,7 @@
 
     <application
         android:name=".MainApp"
-        android:icon="@drawable/icon"
+        android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/Theme.ownCloud"
         android:manageSpaceActivity=".ui.activity.ManageSpaceActivity">

res/xml/authenticator.xml

@@ -19,7 +19,7 @@
 -->
 <account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"
                        android:accountType="@string/account_type"
-                       android:icon="@drawable/icon"
+                       android:icon="@mipmap/ic_launcher"
                        android:label="@string/app_name"
-                       android:smallIcon="@drawable/icon">  
+                       android:smallIcon="@mipmap/ic_launcher">
 </account-authenticator>