move debug resources into debug and cleanup build.gradle

src/debug/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_logo_color_108dp" />
+</adaptive-icon>

src/debug/res/values/ic_launcher_background.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#8F0000</color>
+</resources>

src/debug/res/values/strings.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+Copyright 2010 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+<resources>
+    <string name="app_name">OpenTracks (Debug)</string>
+</resources>