Getting started with container generator

The goal of this last minute PR is to help new developers to get started with a new _container_ application.
Because we don't have action, view or templates generators, it may be cumbersome for developers to figure out where to put things at the beginning.

Proposed changes:
  * `Gemfile` has a `production` group where there is a commented line that suggest an application container (`gem 'puma'`)
  * The welcome page now mentions to edit the routes file as a place to start (see the first screenshot attached).
  * The routes file has now only one route with some explanation (see Routes below).
  * It generates an action, a view and a corresponding template (see the second screenshot attached).

### Routes

```ruby
# Configure your routes here
# See: http://www.rubydoc.info/gems/lotus-router/#Usage
#
#
#
# This route will look for `Web::Controllers::Home::Index` action in `apps/web/controllers/home/index.rb`.
# Please, uncomment the following line to have a working example.
# get '/', to: 'home#index'
```

Once the developer uncomment that line, the application will serve contents from `Home::Index` action and view. 

### Screenshot 1

![screen shot 2014-12-23 at 15 07 30](https://cloud.githubusercontent.com/assets/5089/5538738/5dc824dc-8ab8-11e4-8b1f-8eff721d565c.png)

### Screenshot 2

![screen shot 2014-12-23 at 15 23 41](https://cloud.githubusercontent.com/assets/5089/5538744/70dba42c-8ab8-11e4-802c-e7847d3d6a3a.png)