This allows operators to permit access to Chronograf only to users belonging
to a set of specific Heroku organizations. This is controlled using the
HEROKU_ORGS env or the --heroku-organizations switch.
Information on setting up Heroku and Google authentication has been
added. Also, the information about the design has been updated and moved
to the oauth2 package docs along with updated diagrams to match with
developer expectations about where design-related documentation should
be found.