Fix redis communication

According to the documentation of the protocol http://redis.io/topics/protocol

"A client connects to a Redis server creating a TCP connection to the port 6379. Every Redis command or data transmitted by the client and the server is terminated by \r\n (CRLF)."

This pull request jus fix the module:

```
msf > use auxiliary/scanner/misc/redis_server
msf auxiliary(redis_server) > set RHOSTS X.X.X.X
RHOSTS => X.X.X.X
msf auxiliary(redis_server) > run

[*] Scanning IP: X.X.X.X
[*] Redis Server Information $1071
redis_version:2.4.11
redis_git_sha1:00000000
redis_git_dirty:0
```