Initial support for the REdis Serialization Protocol known as RESP.

Initial support for the REdis Serialization Protocol known as RESP.

This commit adds support for RESP as defined in: http://redis.io/topics/protocol.
It also supports inline commands and pipelining. Due to the popularity of RESP,
numerous services are emerging that use this protocol. You may decode RESP packets
on arbitrary ports using the "-T resp" option.

Example captures can be found in tests/resp_*.

A simple way to test this parser is to start redis-server and then run
redis-cli commands such as "redis-cli set key value".

Traditionally, redis-cli monitor is used to debug redis. Unfortunately,
the "monitor" command can cause significant load on a redis-server in
production. This parser may be used as a non-invasive alternative to
redis-cli monitor.