Modular

## Motivation

I wanted to add other functionality, but I wasn't sure where to do it. There wasn't a centralized class for the application, and everything seemed to be thrown under `bin/annyong`.

Checking out some other gems, like [Rake][https://github.com/jimweirich/rake/blob/master/bin/rake], it seems like the best practice is to keep the bin file short and simple, and have the functionality in an Application class.

## Changes

I moved the options parsing and the server initialization into an `Application` class, to simplify the `bin/annyong` file.