Added sort_by and sort_dir to solr query call to sort by a return field ...

...and choose the sort direction (asc or desc).  Added these options to the search resource along with an option to search metagenomes by md5.  Added job number and PI_lastname to solr schema so we can retrieve that information directly from solr and added those to the search resource.

Note: the sort field passed to the get_solr_query subroutine is actually one of 'field asc' or 'field desc'.  The field and sort direction should be passed in one string separated by a space.