Search exact work
* #2971
search_exact - return empty array when there's no match
* #2971
Adding tests for search_exact
* #2971
Rewrite search_exact for clarity
remove some old code
Don't pass  into search when you don't need it
Move config into API so Xapian doesn't need  passed every time
Update search_exact
* betters args
* more useful return info
Update search_exact tests
Refactor Xapian Search
* Consolidated a few methods
* search, autocomplete, fetch, count_estimate, random -- main methods in Xapian now
Make xapian->fetch more consistent
Didn't update all of nucleotide aligner - new xapian fetch
search_exact -> _search_exact
* demote to helper method
Add comments, move things around
Fix bug
Fix disease fetch bug
Search through aceclass in xapian
Add autocomplete test
Merge branch 'staging' into search-exact
Merge branch 'search-exact' into staging