twitter/twemproxy — pull request #81 by charsyam (2013-03-05 23:38:41+00:00)
Title: redis_auth support

This patch supports redis AUTH Command, but not as User Command.
In req_forward, this patch add auth packet in Request Queue when redis and redis_auth's length is not 0.

so. nc_connection has first flag.

and add redis_auth keyword to conf file to use redis auth.
```c
leaf:
listen: 127.0.0.1:22121
hash: fnv1a_64
redis: true
redis_auth: testpass
distribution: ketama
auto_eject_hosts: true
server_retry_timeout: 2000
server_failure_limit: 1
servers:
- 127.0.0.1:3001:1 server1
- 127.0.0.1:3002:1 server2
```