Modified InterlockingsController to correctly retrieve counts of Signals, Points and Tracks objects belonging to the interlocking
Added #new, #create, #show and #update actions to the SignalsController object in anticipation of being able to create/modify the signals objects in an interlocking

TODO: correct generation of an empty model for the SignalsController#new action and view
TODO: SignalsController#update needs adjusting to perform the correct action to add aspect and ancillary functions to the list and map fields of the Signals model