958023dbb9
This makes it easier to check if the required controller can be found, and automatically raise an error if it is not. Add a #storage_bus method to the StorageController class as a shorthand way to check the general storage controller type.
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.