Implement basic CoffeeScript support

This implements issue #5 by adding basic CoffeeScript support. Sample flight plan:

```coffeescript
Flightplan = require 'flightplan'

plan = new Flightplan()

plan.briefing
  destinations:
    staging:
      host: 'your-server'
      username: 'user'
      password: 'pass'

plan.local (local) ->
  local.log 'Running local...'
  local.ls()

plan.remote (remote) ->
  remote.log 'Running remote...'
  remote.ls()
```