[RFR] Some improvements

- [x] Add `empty-cmd` argument
- [x] Add `golang` container
- [x] Add `python` container
- [x] Add color in gaudi output
- [x] Use declared variables in templates
- [x] Check the current version to download new templates (fixes #47)
- [x] Use first linked container if custom `fastCgi` is not set for an Apache container
- [x] Add a use case for each container/binary
  - [x] apache
  - [x] apache/  php 
  - [x] apache / php / mysql
  - [x] bower
  - [x] couchdb
  - [x] golang
  - [x] jekyll
  - [x] varnish
  - [x] load balancing varnish 
  - [x] nginx
  - [x] nginx/php
  - [x] load balancing nginx
  - [x] Master/slave mysql
  - [x] python / memcached
  - [x] nodejs
  - [x] phpmyadmin
  - [x] php
  - [x] npm
  - [x] composer 
  - [x] postgresql / python
  - [x] silex / hhvm
- [x] Add a `-h` option
- [x] Update doc