GitLab

g5k-api returns two differents Content-Type, for a single item or for
a collection of items. Commit f9ae4214
introduced a regression by always returning "simple" JSON instead of the
g5k-api's specifics Content-Type.
Now, the correct Content-Type will be returned, or application/json if
asked.

Fixes: f9ae4214

The :type, :default and :pattern were not inside schema block

When the `branch` parameter is passed to the versions_controller,
a 404 is returned because g5k-api doesn't find the specified branch.
This is because of a missing concatenation with `origin/`, indeed
g5k-api's reference-repository only holds remote git references.

From from rails 6.0, there is a new method name media_type in
Action::Dispatch class, so it breaked controllers using our helper.