Skip keystone's authentication for additional contrail-clusters request

[rafael-saback]

The annotations field will be necessary for Contrail Insights login, for that reason we need to make it available without the user being authenticated. The cluster type will be defined within the annotations field.

[rafael-saback]

@cijohnson, can you review this PR? I don't have permission to edit the Reviewers field

[buoto]

@rafael-saback This repo is only a mirror. Please post your change on Gerrit (see: https://github.com/Juniper/contrail#how-to-contribute).