Add a service to provide the DataTable instances

[l-lin]

Instead of relying on an event (like catching the event event:dataTableLoaded), it's better to use a service that provides the list of the DataTables that are instanciated.
This feature implies:

• the creation of the service that will provide an array of DT instances along with the directive instance
• the removal of the event event:dataTableLoaded
• the clumsy API dtOptions.reload() will be moved to the directive instance. Indeed, reloading data should not be on the options of the DT. It should rather be within the method of the instance of the directive.
• open opportunities to add new APIs directly to the directive instance