[WIP] Nginx Dockerfile

## WHAT
Nginx in docker container returns `hello world` 

* Dockerfile
 * compile nginx from source
 * add config files

This compile step is heavily inspired from [miketheman/nginx](https://github.com/miketheman/nginx) (Chef cookbook).

## TODO

* [ ] log to stdout
* [ ] compile with http_stub_status_module
* [ ] compile with ngx_small_light module
* [ ] set s3 host via env
* [ ] refactor Dockerfile
* [ ] add serverspec?

## REF

* [[WIP] Install nginx with ngx_small_light #1](https://github.com/wantedly/image-server/pull/1)

```
Syntax:	env variable[=value];
Default:	
env TZ;
Context:	main
```

> By default, nginx removes all environment variables inherited from its parent process except the TZ variable. This directive allows preserving some of the inherited variables, changing their values, or creating new environment variables.
http://nginx.org/en/docs/ngx_core_module.html