setup nginx for load balancing, setting HOME variable in unicorn_init, and fix for missing nginx log directory when web is a non-release role

- (temporary?) fix to problem in unicorn_init script whereby HOME variable is not set (possible alternative to https://github.com/bruno-/capistrano-unicorn-nginx/pull/11)
- create log directory for nginx if web is a non-release role
- connect over TCP/IP if there are multiple app roles and setup nginx for load balancing
> I did test this. I get the same message as you do, but this is only an info message. It does not stop the capistrano script.

Yes - the capistrano script didn't stop for me too.
But I think it's an error on our side to claim all the config files were updated, when **in fact they weren't**.

I'll start a discussion about this in another issue.