Generate a more helpful readme

(#16)

Some of the writing borrowed from [the forthcoming Yeoman introduction walkthrough I'm writing](http://mebutyou.com/#6-10-2013-building-apps-with-the-yeoman-workflow).

Since a generator doesn't necessarily use Grunt or Bower, I didn't go as far as walking through those tools. They were given a shout-out and a link, however.

Let me know what you think. Here's an example of the current output:

---

# generator-ember [![Build Status](https://secure.travis-ci.org/ember/generator-ember.png?branch=master)](https://travis-ci.org/ember/generator-ember)

A generator for [Yeoman](http://yeoman.io).


## What is Yeoman?

Trick question. It's not a thing. It's this guy:

![](http://i.imgur.com/JHaAlBJ.png)

Basically, he wears a top hat, lives in your computer, and waits for you to tell him what kind of application you wish to create.

Not every new computer comes with a Yeoman pre-installed. He lives in the NPM package repository. You only have to ask for him once, then he packs up and moves into your hard drive. *Make sure you clean up, he likes new and shiny things.*

He's a person with feelings and opinions, but he's very easy to work with. If you think he's too opinionated, he can be easily convinced.

For more information about Yeoman, and some party photos of him and his friends [Grunt](http://gruntjs.com) and [Bower](http://bower.io), check out the complete [Getting Started Guide](https://github.com/yeoman/yeoman/wiki/Getting-Started).



## Getting Started with generator-ember

Head to your terminal and make this happen:

```
# Make sure you have yo installed:
$ npm install -g yo

# Install the generator:
$ npm install -g generator-ember

# Run it!
$ yo ember
```


## License

[MIT License](http://en.wikipedia.org/wiki/MIT_License)