Add styles for v23+.

drawableTint attribute works only for Android API 23+.

app/src/main/res/values-v23/styles.xml

+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <style name="AuthenticationEditText" parent="Widget.AppCompat.EditText">
+        <item name="android:layout_width">match_parent</item>
+        <item name="android:layout_height">50dp</item>
+        <item name="android:layout_marginStart">@dimen/screen_edge_left_and_right_margins</item>
+        <item name="android:layout_marginEnd">@dimen/screen_edge_left_and_right_margins</item>
+        <item name="android:paddingStart">@dimen/edit_text_margin</item>
+        <item name="android:paddingEnd">@dimen/edit_text_margin</item>
+        <item name="android:maxLines">1</item>
+        <item name="android:drawablePadding">@dimen/edit_text_drawable_padding</item>
+        <item name="android:drawableTint">@color/colorDrawableTintGrey</item>
+        <item name="android:background">@drawable/style_edit_text</item>
+    </style>
+
+</resources>
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