add signature setting

For multiple users it helps to
keep track about who did what.

app/src/main/res/layout/dialog_event_detail.xml

@@ -61,6 +61,14 @@
 
     </ScrollView>
 
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center_horizontal"
+        android:id="@+id/dialog_event_detail_type_signature"
+        android:layout_marginBottom="5dp"
+        android:visibility="gone"/>
+
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"