Add an OEP-2 compliant openedx.yaml file

openedx.yaml

+# This file describes this Open edX repo, as described in OEP-2:
+# http://open-edx-proposals.readthedocs.io/en/latest/oeps/oep-0002.html#specification
+
+nick: lti
+oeps: {}
+owner: MUST FILL IN OWNER
+track-pulls: true