Ticket #6580: Fix Info parsing and tests

This fixes the parsing of the response of the INFO command on OS X
with the following Redis version:

     Redis server
     v=2.8.11
     sha=00000000:0
     malloc=libc
     bits=64
     build=cd43e547b41f72f

In order to start the `redis-server` with the configuration file
redis.conf I removed everything but the password. The rest will
default to the settings that's used by the version of redis-server
that's installed. This was required as my version of redis-server
wouldn't start with the configuration file as it were.
Ticket #6580: Add support for expiry and existing_value handling of set command
Ticket #6580: Update README slightly.