Implementing GA4GH service-info to DRS

[susheel]

Resolves #309

[dglazer]

@susheel, per the CONTRIBUTING guidelines, we only submit PRs to release branches, not to master. (The main reason is to make sure the Travis CI checks get run, including rebuilding the docs, in each branch -- that way we can be sure the change doesn't break anything, and confirm that the documentation matches the intent.)

[susheel]

@dglazer Done. I have rebased this PR to release/v1.0.1

[dglazer]

@susheel , I'm not an expert on the HubFlow process described in Contributing.MD, but I think the key parts are a) name your feature branch according to the required naming convention, and b) set it up to merge into develop (not a release branch, and not master). @briandoconnor can confirm.

One benefit of that is triggering the Travis CI checks; there are other benefits around the release process that I'm less familiar with.

[susheel]

Done.

[susheel]

GA4GH service-info has just tagged their release v1.0.0 which now makes this PR valid to merge, barring any build and test errors.

[jb-adams]

Reviving this thread as getting /service-info in DRS has been discussed at the past few meetings.

@susheel it would be great if you are still available to work on this PR. The spec was recently migrated from Swagger to OpenAPI, so now there are some merge conflicts. Do you have the bandwidth to update your branch?