agent initialization update

The method of routing RMI requests to an agent plugin changed in gofer 1.0.  It is mapped to a plugin based on which queue the request was received.  The pulp 2.3 plugin used a 1-time scheduled action to read the consumer certificate and initialize the plugin.  Then, monitored the certificate for real-time changes from then on.  If the agent (core) starts processing pending requests before that scheduled action runs and assigns the ID, those requests will fail with *PluginNotFound*.  It's an edge case but it can happen.

The solution is to utilize the gofer 1.0 support for *initializer* methods which are invoked during plugin loading to setup the pulp plugin before requests begin to be processed.  This is a much cleaner approach in all respects.

Also, simplified into plain functions instead of classes.