open struct is not a hash (yet)

fixes CNVS-21597

test plan:
- Run application with ruby 1.9.3.
- Observe that there is no exception when using the new user dashboard.

Change-Id: I791958472836a3c4d3f59b8904253589f8f21134
Reviewed-on: https://gerrit.instructure.com/57469
Tested-by: Jenkins
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Deepeeca Soundarrajan <dsoundarrajan@instructure.com>
Product-Review: Benjamin Porter <bporter@instructure.com>

app/presenters/section_tab_presenter.rb

@@ -21,7 +21,7 @@ def hide?
   end
 
   def path
-    tab[:args].instance_of?(Hash) ? send(tab[:href], tab[:args]) : send(tab[:href], *path_args)
+    tab.args.instance_of?(Hash) ? send(tab.href, tab.args) : send(tab.href, *path_args)
   end
 
   def path_args