Support for CoffeeScriptRedux and source map generation.

The [CoffeeScriptRedux](https://github.com/netzpirat/guard-coffeescript/tree/CoffeeScriptRedux) branch contains an experimental integration of [CoffeeScriptRedux](https://github.com/michaelficarra/CoffeeScriptRedux) and adds support for source map generation, just set the option `:source_map` to `true`. 

The implementation relies on monkey patching [Ruby CoffeeScript](https://github.com/josh/ruby-coffee-script) by installing my fork of [Ruby CoffeeScriptRedux](https://github.com/netzpirat/ruby-coffee-script-redux).

In order to make use of it, you need to add them to your `Gemfile`

```Ruby
gem 'guard-coffeescript', github: 'netzpirat/guard-coffeescript', branch: 'CoffeeScriptRedux'
gem 'coffee-script-redux', github: 'netzpirat/ruby-coffee-script-redux', branch: 'master'
```

This is PR is meant to give you an easy way to play with your Ruby project and CoffeeScriptRedux and will likely not be merged.

You can also use the `:noop` option to verify if your project would compile with CoffeeScriptRedux and give feedback to Michael Ficarra.