twemproxy: version 0.4.1 release

• backend server hostnames are resolved lazily
• redis_auth is only valid for a redis pool
• getaddrinfo returns non-zero +ve value on error
• fix-hang-when-command-only (charsyam)
• fix bug crash when get command without key and whitespace (charsyam)
• mark server as failed on protocol level transiet failures like -OOM, -LOADING, etc
• implemented support for parsing fine grained redis error response
• remove redundant conditional judgement in rbtree deletion (leo ma)
• fix bug mset has invalid pair (charsyam)
• fix bug mset has invalid pair (charsyam)
• temp fix a core on kqueue (idning)
• support "touch" command for memcached (panmiaocai)
• fix redis parse rsp bug (charsyam)
• SORT command can take multiple arguments. So it should be part of redis_argn() and not redis_arg0()
• remove incorrect assert because client could send data after sending a quit request which must be discarded
• allow file permissions to be set for UNIX domain listening socket (ori liveneh)
• return error if formatted is greater than mbuf size by using nc_vsnprintf() in msg_prepend_format()
• fix req_make_reply on msg_get, mark it as response (idning)
• redis database select upon connect (arne claus)
• redis_auth (charsyam)
• allow null key(empty key) (idning)
• fix core on invalid mset like "mset a a a" (idning)