RabbitMqMgment: use WebClient for ListNodes

Apparently ShiftIt is not needed anymore according to Iain, and we
(LockerTeam) are having randome ConnectionRefused problems with this
API, so we think this might fix the issues, or at least bubble up
exceptions that we can understand better.
Revert "renames"

This reverts commit b854c72c908d58b0be745e0c4a37288b4fba4e71.