Add parentheses for explicit operator precedence.

Fixes #1243.

lib/geocoder/sql.rb

@@ -47,8 +47,8 @@ module Geocoder
       spans = "#{lat_attr} BETWEEN #{sw_lat} AND #{ne_lat} AND "
       # handle box that spans 180 longitude
       if sw_lng.to_f > ne_lng.to_f
-        spans + "#{lon_attr} BETWEEN #{sw_lng} AND 180 OR " +
-        "#{lon_attr} BETWEEN -180 AND #{ne_lng}"
+        spans + "(#{lon_attr} BETWEEN #{sw_lng} AND 180 OR " +
+        "#{lon_attr} BETWEEN -180 AND #{ne_lng})"
       else
         spans + "#{lon_attr} BETWEEN #{sw_lng} AND #{ne_lng}"
       end