revert to Material after considering DeviceDefault

Author: Hisanobu Tomari

app/src/main/res/values-v21/styles.xml

@@ -1,5 +1,5 @@
 <resources>
-	<style name="AppBaseTheme" parent="android:Theme.DeviceDefault.Light">
+	<style name="AppBaseTheme" parent="android:Theme.Material.Light">
 		<item name="android:colorPrimary">@color/primary</item>
 		<!--   darker variant for the status bar and contextual app bars -->
 		<item name="android:colorPrimaryDark">@color/primary_dark</item>