starting on the data storage for plugins.
Beginnings of a plugin manager.

* /plugins_manager is now a valid URL and lists the plugins.
* plugins are defined as services and are compiled (in the
symfony sense) and added to a plugin manager automatically.
* plugins are now container aware.
* plugins must provide a getName and getDescription method.
* and the beginnings of a plugin data store and the crud stuff
to go with it.
debug code begone.
cleanup the extension loader a little bit.
no need to crud the plugins or plugindata.
more progress on the plugins.