fixing edx_sandbox play

playbooks/edx-east/edx_sandbox.yml

@@ -9,10 +9,8 @@
   sudo: True
   gather_facts: True
   vars:
-    migrate_db: True
+    migrate_db: "yes"
     mysql5_workaround: True
-  vars_files:
-    - "{{ secure_dir }}/vars/edx_sandbox.yml"
   roles:
     - common
     - nginx