Add an OEP-2 compliant openedx.yaml file

[cpennington]

This adds an openedx.yaml file, as described by OEP-2:
http://open-edx-proposals.readthedocs.io/en/latest/oeps/oep-0002.html

The data in this file was transformed from the contents of
edx/repo-tools-data:repos.yaml

[coveralls]

Coverage remained the same at 98.507% when pulling 63fd009 on add-openedx-yaml into fee33f4 on master.

[coveralls]

Coverage remained the same at 98.507% when pulling 67a088f on add-openedx-yaml into fee33f4 on master.

[coveralls]

Coverage remained the same at 98.507% when pulling 67a088f on add-openedx-yaml into fee33f4 on master.

[coveralls]

Coverage remained the same at 98.507% when pulling 67a088f on add-openedx-yaml into fee33f4 on master.

[cpennington]

@edx/analytics: This one is yours too.

[coveralls]

Coverage remained the same at 98.507% when pulling 1f76033 on add-openedx-yaml into fee33f4 on master.

[dsjen]

👍