Changing octets doesn't change address

[realloc]

When I change a value in .octets I expect the .address to be changes. Than doesn't occur.
Version 0.8.0 is used.

realloc@support01:/var/tmp$ irb
1.9.3-p194 :001 > require 'ipaddress'
 => true 
1.9.3-p194 :002 > ip = IPAddress("172.16.10.1/24")
 => 172.16.10.1 
1.9.3-p194 :003 > ip.address
 => "172.16.10.1" 
1.9.3-p194 :004 > ip.octets[2]=11
 => 11 
1.9.3-p194 :005 > ip.address
 => "172.16.10.1" 
1.9.3-p194 :006 > ip[2]
 => 11 
1.9.3-p194 :007 > 

[mikemackintosh]

I think this is a legit concern, and causes confusion if you can read an octet or group using [], but cannot write. As of 0.8.1, a IPv4/6#[]= method didn't exist.

I have added this to both classes, IPv4 and IPv6, and will be including it into 0.8.2

[mikemackintosh]

This has been included here - #61