GitLab

This route causes the node controller to fail with "No route matches"
error when requesting nodes for a cluster.

Refresh fake reference-repository

See merge request !78

Return 404 when a commit or a branch cannot be found

See merge request !77

Add the ability to return a deep view of reference-repository

See merge request !74

This allow to get a deep view of the reference api by passing the
`deep` GET parameters to the request.
It is also possible to request a single site or the specific list of nodes
assigned to an OAR job id.

The controller was usefull when environments were stored inside
reference-repository.

Remove g5k-api's UI

See merge request !75

Since the UI is not actively maintained and not used, we decided to remove it.

Add two new GET parameters to request reference api by date

See merge request !73

Instead of using version, this commit add timestamp and date
parameters

By default, Net::HTTP perform a retry in some case (for example when a
ReadTimeout occures).