uipcps: ceft dft: allow any replica to respond to M_READ requests
uipcps: ceft dft: allow any replica to respond to M_READ requests

Clients select the first reader that responds in addition to
tracking the leader (for write requests).
Fixes #65.

vmaffione/rlite,vmaffione/rlite,autrimpo/rlite,autrimpo/rlite,autrimpo/rlite,vmaffione/rlite,vmaffione/rlite,autrimpo/rlite