Always enable  when celluloid/rspec is included
Revert "[BUG] ActorProxy doesn't respond_to respond_to? correctly" #303

This reverts commit e4c2ade6c204f2a3eb4bc070cd18de68e361aa8e.
__class__ for all AbstractProxy descendants

This provides access to the current proxy class for classes which inherit from
Celluloid::AbstractProxy. This can be used for methods that need reflection.
Implement #respond_to? on SyncProxy

Check the instance methods of the proxy class first when responding to
respond_to?

If that fails, ask the actor if it responds to the given method.
[BUG] ActorProxy doesn't respond_to respond_to? correctly
Remove explicit method_missing thunks

These methods previously overrode definitions on Object. Now that ActorProxy is
BasicObject-derived, they can be removed.
Merge pull request #305 from celluloid/nuke-unnecessary-proxy-methods

Remove explicit method_missing thunks
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
Raise on JRuby 1.7.3 warning Celluloid is broken

After helping someone debug this *again* today I think our best bet is
to simply have Celluloid raise if someone tries to require it on JRuby
1.7.3:

    $ bundle exec irb -rcelluloid
    RuntimeError: Celluloid is broken on JRuby 1.7.3. Please upgrade to
    1.7.4+
Merge pull request #307 from celluloid/blow-up-on-jruby-173

Raise on JRuby 1.7.3 warning Celluloid is broken
Specify full path for sysctl on darwin hosts
Merge pull request #308 from amrik/master

Specify full path for sysctl on darwin hosts
remove empty lines