Add ImageField demo to example app

Author: insspb

example_app/binary_demo.py

@@ -10,6 +10,7 @@ class BinaryDemoModel(db.Document):
     binary_field = db.BinaryField()
     binary_field_with_default = db.BinaryField(default=lambda: "foobar".encode("utf-8"))
     file_field = db.FileField()
+    image_field = db.ImageField()
 
 
 def binary_demo_view(pk=None):

example_app/templates/layout.html

@@ -23,7 +23,7 @@
     <li><a href="{{ url_for("dates_demo_view") }}">DateTime demo</a></li>
     <li><a href="{{ url_for("boolean_demo_view") }}">Booleans demo</a></li>
     <li><a href="{{ url_for("dict_demo_view") }}">Dict/Json demo</a></li>
-    <li><a href="{{ url_for("binary_demo_view") }}">Binary demo</a></li>
+    <li><a href="{{ url_for("binary_demo_view") }}">Binary/Files/Images demo</a></li>
   </ul>
 </nav>
 <div>