added db.serialize to wrap 1.find maximum population and 2.find cities that match prefix queries, fixing random occurrence of null scores in JSON bug.
replace db.serialize fix with a flag based solution for synchronization, with the advantage of letting queries run in parallel. Also changed timeout html code from 404 to 503/server busy.
replace db.serialize fix with a flag based solution for synchronization, with the advantage of letting queries run in parallel. Also changed timeout html code from 404 to 503/server busy.