Update openedx.yaml (#137)

* Reflects new sub-team-based ownership model.
* Puts `owner` value in line with updated OEP-2.
* Also updates values of `tags` and `oeps`.

openedx.yaml

@@ -2,8 +2,12 @@
 # http://open-edx-proposals.readthedocs.io/en/latest/oeps/oep-0002.html#specification
 
 nick: grbk
-oeps: {}
+tags:
-owner: schenedx
+  - frontend-app
-supporting_teams:
+  - masters
-  - masters-devs
+oeps:
+  oep-2: true    # Repository metadata
 openedx-release: {ref: master}
+owner:
+  type: team
+  team: edx/masters-devs-gta