(bug 43238) Add very simple weighting for entity search

A very simple weighting algorithm (number of sitelinks) has
been added to do a post-DB-query ranking of search results.
Also, this limits the search to 5000 items.

DEPLOYMENT NOTE: When deploying without a database update, 
set 'withoutTermWeight' => true.

Change-Id: Ie09e4932de42676dd5d638d32f76abe0a2200617
Merge "(bug 43238) Add very simple weighting for entity search"