API: /namedspaces/{userName} to support sort and filter

[dlabrecq]

The existing /namedspaces/{userName} API does not support server-side sort and filtering.

FYI, I'm in the process of implementing the UXD design below for the my spaces page.
https://redhat.invisionapp.com/share/DQDSL22JA#/screens/261389228

In order for the toolbar to sort and filter properly, the list component cannot use infinite scroll. All the user's spaces are currently sorted and filtered client-side.

If the API supported sort and filtering, we could introduce an infinite scroll.

[joshuawilson]

cc @aslakknutsen