Add enterprise subsidy to devstack

[mfarhan943]

Related Ticket:
#76

Related PR:
openedx/enterprise-subsidy#319

Tasks

Beta Give feedback

1. Add the service in docker-compose.yml file, follow docker-compose.yml file from the source repo.
2. Add dev.shell make command if some extra env variables need to be set
3. Add an entry in check.sh if needed
4. Mount volume in docker-compose-host.yml file
5. Add entry in options.mk file
6. Create provision-IDA_NAME.sh file if needed. Also, add an entry in provision.sh file.
7. Create table in provision.sql file if needed
8. Add an entry in repo.sh file.
9. Add an entry in service_list.rst file.

[iamsobanjaved]

Just a few suggestions, rest looks good.

[mfarhan943]

Just a few suggestions, rest looks good.

I have applied the suggestions.