Replaced all of the app/views/*/index.js.erb templates (which are
nearly all the same) with the layout
app/views/layous/application.js.erb.
Get the 'record per page' select control to work by passing its value to the pagination method.
Factored the search forms out of the index_table partials into the shared partial 'search_form'.
Fixed the sort_column method so that it works correctly with the search controller and the species controller.
In index: Set @iteration and define respond_to for js format to get
Ajax searches to work.  Set @users to actually use the search
parameter.

Defined as helper methods "sort_column" and "sort_direction", which
the Ajax template needs.
Make User extend SimpleSearch and add scopes and constants needed for the search machinery.
Factored the search forms out of more of the index_table partials into the shared partial 'search_form'.
For more of the controllers: Get the 'record per page' select control to work by passing its value to the pagination method.
Merge branch 'SearchCleanup'