added monitoring interface
take 2
automatically enable monitoring when required
reworked exposed api
use internal notifications system
provide an api call to start the probe "system"
added probe tests
reworked probe tests to get rid of timing issues
remove empty lines
probe refactor
removed  reset from celluloid.rb
check if actor exists before calling it
newline
Merge pull request #284 from schmurfy/monitoring_api

added monitoring interface