Add missing accent color for API < 21

Author: rubengees

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

@@ -4,6 +4,7 @@
     <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
         <item name="colorPrimary">@color/primary</item>
         <item name="colorPrimaryDark">@color/primary_dark</item>
+        <item name="colorAccent">@color/accent</item>
         <item name="android:textColorPrimary">@color/primary_text</item>
         <item name="android:textColorSecondary">@color/secondary_text</item>
         <item name="preferenceTheme">@style/PreferenceThemeOverlay</item>