Remove view registry references from the workspace model layer

Removed various ::getView methods from the model. Using the atom.views
global in the views for now, but going to switch them over to using a
locally assigned view registry instead in a subsequent commit.

src/pane-axis.coffee

@@ -39,9 +39,6 @@ class PaneAxis extends Model
 
   getOrientation: -> @orientation
 
-  getView: (object) ->
-    @container.getView(object)
-
   getChildren: -> @children.slice()
 
   getPanes: ->