Be explicit about the path to course.xml

before, we guessed by splitting the course id.  This is fragile and
doesn't handle the new export format which contains a course/ subdir

playbooks/roles/testcourses/tasks/deploy.yml

@@ -21,7 +21,7 @@
 
 - name: import the test courses
   shell: >
-    {{ demo_edxapp_venv_bin }}/python ./manage.py cms --settings=aws import {{ demo_edxapp_course_data_dir }} /var/tmp/{{ item.path|basename }}/{{ item.course_id.split('/')[2] }}
+    {{ demo_edxapp_venv_bin }}/python ./manage.py cms --settings=aws import {{ demo_edxapp_course_data_dir }} /var/tmp/{{ item.path|basename }}/{{ item.xml_path }}
     chdir={{ demo_edxapp_code_dir }}
   sudo_user: "{{ common_web_user }}"
   with_items: TESTCOURSES_EXPORTS