Add trello migration config

config.yml.sample

@@ -174,7 +174,7 @@ migration:
   todoist:
     # Wheter to enable the todoist migrator or not
     enable: false
-    # The client id, required for making requests to the wunderlist api
+    # The client id, required for making requests to the todoist api
     # You need to register your vikunja instance at https://developer.todoist.com/appconsole.html to get this
     clientid:
     # The client secret, also required for making requests to the todoist api
@@ -185,6 +185,20 @@ migration:
     # with the code obtained from the todoist api.
     # Note that the vikunja frontend expects this to be /migrate/todoist
     redirecturl:
+  trello:
+    # Wheter to enable the trello migrator or not
+    enable: false
+    # The client id, required for making requests to the trello api
+    # You need to register your vikunja instance at  to get this
+    clientid:
+    # The client secret, also required for making requests to the trello api
+    clientsecret:
+    # The url where clients are redirected after they authorized Vikunja to access their trello cards.
+    # This needs to match the url you entered when registering your Vikunja instance at trello.
+    # This is usually the frontend url where the frontend then makes a request to /migration/trello/migrate
+    # with the code obtained from the trello api.
+    # Note that the vikunja frontend expects this to be /migrate/trello
+    redirecturl:
 
 avatar:
   # When using gravatar, this is the duration in seconds until a cached gravatar user avatar expires

pkg/config/config.go

@@ -118,6 +118,10 @@ const (
 	MigrationTodoistClientID        Key = `migration.todoist.clientid`
 	MigrationTodoistClientSecret    Key = `migration.todoist.clientsecret`
 	MigrationTodoistRedirectURL     Key = `migration.todoist.redirecturl`
+	MigrationTrelloEnable           Key = `migration.trello.enable`
+	MigrationTrelloClientID         Key = `migration.trello.clientid`
+	MigrationTrelloClientSecret     Key = `migration.trello.clientsecret`
+	MigrationTrelloRedirectURL      Key = `migration.trello.redirecturl`
 
 	CorsEnable  Key = `cors.enable`
 	CorsOrigins Key = `cors.origins`
@@ -288,6 +292,7 @@ func InitDefaultConfig() {
 	// Migration
 	MigrationWunderlistEnable.setDefault(false)
 	MigrationTodoistEnable.setDefault(false)
+	MigrationTrelloEnable.setDefault(false)
 	// Avatar
 	AvatarGravaterExpiration.setDefault(3600)
 	// List Backgrounds