[jsapp] Show 'Untitled View' if no page name
[api] permit PUT updates to page/$id/column to replace collection

 * This is actually a handy thing for the jsapp to do, so allow it.  As
   a side effect it is no longer a 422 error to pass both a 'widgets' and
   'template' data keys.  If done, the 'widgets' key takes priority.

 * POST semantics remain the same. A single hashref POSTed to
   pages/$id/columns acts as a single create resource request.  Passing
   an arrayref is still a 422 error.
[jsapp] make add/del page columns need "Save" button

 * The add column / delete column commands used to operate independently
   of the "Save" button.  This change now makes them only be saved after
   the "Save" button is pressed.