Description of problem:
Per page pull-down in Configure -> Tasks page doesn't do anything

Version-Release number of selected component (if applicable):
CFME 5.3

How reproducible:
Always

Steps to Reproduce:
1. Navigate to Configure -> Tasks
2. Select either of the available tasks tabs (you need to see a non-empty
   task list, i.e. you need to have some actual tasks created beforehand)
3. Change the per-page settings in the displayed list

Actual results:
The new per-page settings won't do anything.

The following error displays in application's log:

ActionController::RoutingError (No route matches [POST] "/miq_proxy/change_tab"

Expected results:
The per-page settings works correctly.

Additional info:
https://github.com/ManageIQ/manageiq/issues/818