Modified redisd to notify for eth0 ip change,issue 80

[atmecs123]

Event is generated in netlink.go and it is notified to redisd for eth0 ip change.Old connection is closed.

Before change =
siddhant@invader41:~$ netstat -nlp | grep 6379
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 172.17.2.31:6379 0.0.0.0:* LISTEN -
tcp 0 0 127.0.0.1:6379 0.0.0.0:* LISTEN -
tcp6 0 0 fe80::5218:4cff:fe:6379 :::* LISTEN -
tcp6 0 0 ::1:6379 :::* LISTEN -

After change=
siddhant@invader41:~$ netstat -nlp | grep 6379
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 172.17.2.95:6379 0.0.0.0:* LISTEN -
tcp 0 0 127.0.0.1:6379 0.0.0.0:* LISTEN -
tcp6 0 0 fe80::5218:4cff:fe:6379 :::* LISTEN -
tcp6 0 0 ::1:6379 :::* LISTEN -

Connect through redis-cli from i29 with changed ip.
siddhant@invader29:~$ redis-cli -h 172.17.2.95
172.17.2.95:6379>

[atmecs123]

@fszyang @dlobete Please review the changes for issue 80.