Feature/plugins see command line args

@mglazer,

this is my first attempt at building a solution to your problem in #12 

- i'm not very happy with the tight coupling and poor abstractions in `Platform` and `Application`. they need work :(
- i've added a `CliSimpleApplication` that lets you set the args at construction. that way you can access them when you're creating your plugins, which means the plugins themselves can use it.

questions:

1. thoughts in general about this approach?
2. would we want to squish `CliSimpleApplication` with `SimpleApplication`?
3. would you want the args injected in ever?

thanks