v0.2.5

#86 Randomly pick up the node used to update slots
#88 Fix duplicate client_eof caused by connection timeout
#87 Support slowlog command
#90 Add cluster name, pid, port to log
#91 Send slow command to statsd
#92 Use atomic operation to manipulate stats cumulation for safety
#93 Fix invalid resp in 'proxy info' command
#96 Amend response format of 'proxy info'
#94 Ignore command with error result in slowlog. Fix some bugs