Clean-up of 'eventlogging::monitor' class.

This is a last in a series of clean-up commits to the EventLogging Puppet
module. This patch updates the module to reflect changes in the Ganglia metric
module which is bundled with EventLogging. Rather than hard-code stream URIs in
the metric module's .pyconf file, the updated metric module automatically
infers stream URIs and declares metrics by reading EventLogging's configuration
files.

Change-Id: I1691bdfbf627169b1709017aefdd5a7be92cfbd1
Merge "Clean-up of 'eventlogging::monitor' class." into production