Allow Plugins to add to Blesta Event Language Strings

[Chance]

When developing plugins that provide custom actions and events, it would be good if admins could see a native description of what a Blesta event is for, AND allow other plugins to ADD to that description.  For instance, the language string for AppController.structure simply reads:

[AdminCompanyPlugins.settings.event.appcontroller.structure] = 'This event is triggered when a page load occurs that is not via AJAX.'

If plugins were able to add additional description, the description for this event might look something like this:

This event is triggered when a page load occurs that is not via AJAX.  The 'XYZ' plugin uses this event to make the 'XYZ' action_staff_client link open in a Blesta modal, rather than loading an entirely new web page.

Ideally, it would be nice to have a plugin define this added verbiage.  Something like this in its xyz_plugin language file:

[AdminCompanyPlugins.settings.event.appcontroller.structure] .= "The 'XYZ' plugin uses this event to make the 'XYZ' action_staff_client link open in a Blesta modal, rather than loading an entirely new web page."

By simply adding to the existing description, the default Blesta language string is kept, and EACH plugin that handles the event has the ability to append to the description.  

This would be an added benefit because it would allow users to have a brief idea of what each plugin does with that event.  This way if an admin chooses to enable/disable the event, they have more insight into precisely what they are enabling/disabling.