Merge pull request #9 from yibeichan/main

add subject id, remove unused files

Author: yibeichan

activities/demo/demo_schema

@@ -14,6 +14,10 @@
     "version": "0.0.1",
     "ui": {
         "addProperties": [
+            {
+                "isAbout": "demo:src_subject_id",
+                "variableName": "src_subject_id"
+            },
             {
                 "isAbout": "demo:interview_age",
                 "variableName": "interview_age"
@@ -24,6 +28,7 @@
             }
         ],
         "order": [
+            "demo:src_subject_id",
             "demo:interview_age",
             "demo:sex"
         ],