* do not set default order by to post_date_gmt if it's not set in WP_Query
* use a ranking expression that gives preferences to matches in post titles
* fixed a bug where we glob hyphenated words into one word, which screws up a search.
get the sphinx ranker from the config file. (it defaults to proximity_bm25.)
use the default order of post_gmt_date unless we have a keyword search
Merge pull request #31 from wluo/github-3248

improved ranking plus a bug fix