Disable IPv6 support for Nginx

On some servers, IPv6 is not available, so Nginx can't listen on  [::]:80 

	2014/12/19 07:18:32 [emerg] 484#0: socket() [::]:80 failed (97: Address family not supported by protocol)

I removed the line and the container start successfully.
Merge pull request #6 from ahmet2mir/patch-1

Disable IPv6 support for Nginx