The current API allows listings of the neturon server
version without authentication. Because pecan was treating
this like a normal controller, it was requiring keystone
authentication.
This adjusts the version listing to behave as a wrapper so
it can be placed outside of the keystone authentication
wrapper to allow anonymous queries.
Closes-Bug: #1556038
Change-Id: I9f5aa3bea0e11c5e179fc286f9fa350b3930364f