Boost search records that have mz:is_current=1
Boost search records that have mz:is_current=1

re: #40

whosonfirst/whosonfirst-www-boundaryissues,whosonfirst/whosonfirst-www-boundaryissues,whosonfirst/whosonfirst-www-boundaryissues,whosonfirst/whosonfirst-www-boundaryissues