redmine task #1908 fixes search on posterior table

<a href="https://ebi-forecast.igb.illinois.edu/redmine/issues/1908">redmine #1908</a> 
I've already pulled this request, but I now discover that I can't get the test starting here to pass.  Were you able to?  It seems that in the rspec test environment, merely filling in the search box doesn't trigger a search.  So unless the posteriors table is empty to begin with, we won't see "No entries" on the page.