features/marker: log message clean up

1. Changed log messages to be more appropriate.
2. Changed loglevel of failures in fop_cbks to be recorded as TRACE.
   Logging of failures at higher loglevels is unessential in non-endpoint
 translators.
3. Removed a log message related to memory allocation failure.

BUG: 1174087
Change-Id: I63c560c3bbd12706357fb3f696378c1a1e1efb44
Signed-off-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-on: http://review.gluster.org/8168
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
Tested-by: Raghavendra G <rgowdapp@redhat.com>