cluster/afr: move messages to new logging framework

Change important (from a diagnostics point of view) log messages to use
the gf_msg() framework.

Change-Id: I0a58184bbb78989db149e67f07c140a21c781bc2
BUG: 1075611
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-on: http://review.gluster.org/7784
Reviewed-by: Krutika Dhananjay <kdhananj@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Pranith Kumar Karampuri <pkarampu@redhat.com>