Remove unnecessary notifyAll calls

If there were entries in the Space under a given queue, there's
no need to call notifyAll. This change improves performance in heavy
loaded systems queueing transactions to single queues.
expose Configuration object under 'cfg' name

[ci skip]
QConfig register its configuration with the NR

Q2 pushes Configuration objects to Configurable QBeans, but
in situations where non Q2 code has to be used (i.e. servlets)
this QConfig service allow us to 'pull' the configuration by
locating the Configuration object in the NameRegistrar.

We suggest to avoid using this when possible as the push configuration
is usually better.

[ci skip]