Rewrite logging code to be cleaner
Rewrite logging code to be cleaner

The logging code in handoff sender was unnecessarily complex.  Also,
it's better not to use a helper function as it obfuscates _where_ the
logging statement was actually made.  I.e. lager will always print the
name of the helper fun and not where the call was actually originated
from.

Kyorai/riak_core