write slow query log to file instead of stderr
rename slow_query_file -> slow_query_log_path
limit length of slow query output
slow query log can be output as plain text or json
show slow_query_log_format in neostat
Merge remote branch 'pixiv/slow_query_log'
initialize struct sockaddr_in 0

inet_ntoa expects struct sockaddr_in is initialized to 0
append description of new paramenter in doc

 * worker_map
 * slow_query_sec
 * slow_query_log_path
v0.6.1 released