MightyBox Settings Manager: Settings Form and centralized plugin storage scheme

Specific customizable settings for MightyBox should be editable by the Settings form of MightyBox. These settings will need to persist between instances of MightyBox. In order to create one centralized "portfolio" of settings for external plugins which may need settings, the SettingsManager will persist its settings in a Dictionary<key, Dictionary<key,value>> where the inner dictionary is the settings for a plugin by key and serializable object. In this way there will be API hooks for a plugin to store and retrieve their settings from the SettingsManager. Plugins will be able to allow the user to handle the plugin settings by exposing (a window / UserControl) for the SettingsForm to display.