Publish a .well-known/assetlinks.json

This is required (in some cases? Because many seem to work) to publish
deep links on modern android versions. Basically we tie in the
publishing certificate we use in the play store to our domain, thereby
allowing it to "capture" those links directly.

Per complaints from the play console, and their suggested fix.

postgresqleu/urls.py

@@ -406,6 +406,9 @@
     # Monitoring endpoints
     url(r'^monitor/git/$', postgresqleu.util.monitor.gitinfo),
     url(r'^monitor/nagios/$', postgresqleu.util.monitor.nagios),
+
+    # Digital assets needed to do deep-linking in the android app.
+    url(r'^.well-known/assetlinks.json$', postgresqleu.util.views.assetlinks),
 ])
 
 if settings.ENABLE_NEWS:

postgresqleu/util/views.py

@@ -8,6 +8,8 @@
 from postgresqleu.util.messaging.twitter import process_twitter_webhook
 from postgresqleu.util.markup import pgmarkdown
 
+import json
+
 
 # Anybody logged in can do a markdown preview, since it's a safe operation
 # and this way we don't need any db access.
@@ -34,3 +36,23 @@ def messaging_webhook(request, providerid, token):
 @csrf_exempt
 def twitter_webhook(request):
     return process_twitter_webhook(request)
+
+
+# Assetlinks to confirm to Google Play that we are the authors of our Android app
+# (contents of file are suggestions from google play console)
+def assetlinks(request):
+    return HttpResponse(
+        json.dumps([
+            {
+                "relation": [
+                    "delegate_permission/common.handle_all_urls"
+                ],
+                "target": {
+                    "namespace": "android_app",
+                    "package_name": "eu.postgresql.android.conferencescanner",
+                    "sha256_cert_fingerprints": [
+                        "F3:F7:29:8B:4D:B4:2E:9E:B8:3B:C6:E3:8B:C0:69:FE:19:9E:2C:24:D4:6B:AE:C7:1E:83:D7:07:47:7E:CA:EB"
+                    ]
+                }
+            }
+        ]), content_type='application/json')