State Aware Plugin Module Descriptors

When implementing PLUG-18, it became clear that it would be better architectually to have the ModuleDescriptor's trigger the module object classes' StateAware interface code as it would allow them to retain the control and better determine how instanciation / triggering takes place. This means that the modules in confluence which override the enabled/disabled() methods will need to call super.enabled/disabled() (or otherwise trigger the module object) in order for them to work as planned.

The confluence and atlassian-plugins patches can be applied separately, with only the confluence patch depending on the plugins patch (and not visa versa).