- Change 'client' nested resrouces from deeply nested to nested resource.

this commit changes the client resource deeply nested under clients (clients.client)  to simple nested resource (client) to reset the name space (the namespaced Routes, Controllers and templates)
- WIP, SalesReps.
- Add salesReps API controller & Route (Back-End) .
-Add sales_rep route (Ember) & serializer (Back-end).
-List sales-reps .
-WIP, Showing a salesRep.
-Delete unused templates (old deeply nested salesRep templates).
-WIP, Editing a sales-rep.