Revision 209563

Working on: MNG-377

o Added component descriptor for the MavenPluginMappingBuilder

o Added a new ComponentDiscoveryListener implementation to factor the DefaultPluginManager out of the plexus.xml for maven-core...the DefaultPluginManager now delegates to this component for plugin registration/lookup/etc. and has proper component requirements.

o Moved the DefaultPluginManager component declaration into components.xml, and added a component definition for MavenPluginCollector to plexus.xml in maven-core

Next step is to get rid of the old pluginKey junk, and start using o.a.m.Plugin instances to hold g:a:v info for all plugins in the system...this will make the interface cleaner and remove the need to concat/parse the plugin identity. Then, I'll add the mapped-plugin lookup functionality to the lifecycle executor.