Implement worker

Closes #2 (closed)

.arkindex.yml

@@ -11,14 +11,14 @@ workers:
       build: Dockerfile
     user_configuration:
       train_folder_id:
-        type: str
+        type: string
         title: ID of the training folder on Arkindex
         required: true
       validation_folder_id:
-        type: str
+        type: string
         title: ID of the validation folder on Arkindex
         required: true
       test_folder_id:
-        type: str
+        type: string
         title: ID of the testing folder on Arkindex
         required: true