Use PhutilQueryCompiler in Phabricator fulltext search
This means that ft_boolean_syntax no longer needs to be configured (we'll just do the right thing in all cases).
- Ran various queries in the UI, saw the expected results.
- Ran bad queries, got useful errors.
- Searched threads in Conpherence.
Reviewed By: chad
Differential Revision: https://secure.phabricator.com/D16939