Pull PluginManager from dependency injection framework

Plugin manager used to be initialized globally in its
own block, which is what of the dep inj framework does
nicely.

The dep injection now creates the plugin manager as a
singleton.
922871: Call pre_product_id_install hook on product install

The hook is now being called, and the conduit will recieve
the list of products that are to be installed.
Make PluginManager lazy loading
Merge pull request #643 from candlepin/mstead/plugin-pre-product-id-install

922871: Call pre_product_id_install hook on product install