Add logging filter to not raise error when monitoring transient nodes. [JIRA: RIAK-2373]

[pyrrho]

https://github.com/basho/riak_core/blob/develop/src/riak_core_dist_mon.erl#L81

For example, when the dist mon attempts to monitor nodes created to perform riak-admin test operations, it often spit out spurious errors in the form.

@riak_core_dist_mon:handle_info:81 Could not get dist for 'riak_test@<node_name>'

Basho folks, related ZenDesk ticket number: 13033

[jonmeredith]

also impacts riak_core_tcp_mon in riak_repl.