Add support for Mercurial repositories

Review Request #9409 — Created Nov. 29, 2017 and submitted — Latest diff uploaded

Information

rb-gateway
master
974ed29...

Reviewers

RB Gateway now supports Mercurial repositories. Setting scm to hg
in a repository entry in the configuration file will enable this
behaviour.

Co-authored-by: Henri-Philippe Marceau hmarceau@laurentian.ca

Ran go fmt ./....
Ran go test ./....

Configured a Mercurial repository and made HTTP requests to verify
API responses were correct.