Handle case of missing dash.fingerprint module (#192)

* Add contributor

* Handle missing module in older dash versions

CONTRIBUTIONS.md

@@ -27,3 +27,5 @@ Thanks to the following people:
 [dwinston](https://github.com/dwinston)
 
 [gianlucasalvato](https://github.com/gianlucasalvato)
+
+[tiagoslg](https://https://github.com/tiagoslg)

django_plotly_dash/views.py

@@ -28,7 +28,14 @@
 
 from django.http import HttpResponse, HttpResponseRedirect
 from django.shortcuts import redirect
-from dash.fingerprint import check_fingerprint
+
+try:
+    from dash.fingerprint import check_fingerprint
+except:
+    # check_fingerprint not available, fake it
+    def check_fingerprint(resource):
+        return resource, None
+
 
 from .models import DashApp
 from .util import get_initial_arguments, static_path