Add download link on deprecation dialog

lib/helpers/server_config_helper.dart

@@ -24,6 +24,8 @@ class ServerConfigurationHelper {
       minSupportedMobileVersion:
           Version.parse(response["min_supported_mobile_version"]),
       termsURL: response["terms_url"],
+      playStoreURL: response["play_store_url"],
+      androidDirectDownloadURL: response["android_direct_download_url"],
       passwordPolicy: PasswordPolicy(
         allowMailInPassword: passwordPolicy["allow_email_in_password"],
         allowNameInPassword: passwordPolicy["allow_name_in_password"],

lib/models/server_config.dart

@@ -60,16 +60,22 @@ class ServerDataConservationPolicy {
 class ServerConfig {
   final Version minSupportedMobileVersion;
   final String termsURL;
+  final String playStoreURL;
+  final String androidDirectDownloadURL;
   final PasswordPolicy passwordPolicy;
   final ServerDataConservationPolicy dataConservationPolicy;
 
   const ServerConfig({
     @required this.minSupportedMobileVersion,
     @required this.termsURL,
+    @required this.playStoreURL,
+    @required this.androidDirectDownloadURL,
     @required this.passwordPolicy,
     @required this.dataConservationPolicy,
   })  : assert(minSupportedMobileVersion != null),
         assert(termsURL != null),
+        assert(playStoreURL != null),
+        assert(androidDirectDownloadURL != null),
         assert(passwordPolicy != null),
         assert(dataConservationPolicy != null);
 }

lib/ui/dialogs/deprecation_dialog.dart

@@ -1,5 +1,7 @@
+import 'package:comunic/helpers/server_config_helper.dart';
 import 'package:comunic/utils/intl_utils.dart';
 import 'package:flutter/material.dart';
+import 'package:url_launcher/url_launcher.dart';
 
 /// Deprecation dialog
 ///
@@ -16,11 +18,21 @@ class _DeprecationDialog extends StatelessWidget {
     return AlertDialog(
       title: Text(tr("Deprecated application version")),
       content: Text(tr(
-          "This version of the mobile application is deprecated. You might still be able to use it, but some features will not work. We recommend you to update to the latest version of the application.")),
+          "This version of the Comunic application is deprecated. You might still be able to use it, but some features may not work. We recommend you to update to the latest version of the application.")),
       actions: [
+        MaterialButton(
+          onPressed: () =>
+              launch(ServerConfigurationHelper.config.playStoreURL),
+          child: Text(tr("Go to the Play Store")),
+        ),
+        MaterialButton(
+          onPressed: () =>
+              launch(ServerConfigurationHelper.config.androidDirectDownloadURL),
+          child: Text(tr("Download update outside Play Store")),
+        ),
         MaterialButton(
           onPressed: () => Navigator.pop(context),
-          child: Text(tr("OK")),
+          child: Text(tr("Use the old application anyway")),
         )
       ],
     );