Fix node refresh when peers is empty.

[ close mongoid/mongoid#2831 ]
ADDED: No-operation isntrumenter
CHANGED: node to use provided instrumenter
Merge branch 'master' into feature/activesupport-notifications
ADDED: Logging instrumenter
Changed logging class -> removed unused calls
Reverted to logger usage
Fixing minor errors
Changed LoggingInstrumenter to talk to logging module