Fix account search when SiteAccountSearch subclass has a join clause

If the search is subclassed, and the where clause is dependant on the join clause, the index would throw an error on loading the count for the pager. Use the join clause in that query to prevent this. As well, remove the id reference, which is ambigious.
Merge pull request #4 from silverorange/fix-account-search-with-joins

Fix account search when SiteAccountSearch subclass has a join clause