Install help

What do you guys think of this? Basically this branch adds a post-install message like this:

```
/--------------------------------------------------------------------------\
|                                                                          |
|  Tower is installed!                                                     |
|                                                                          |
|  Create an app:                                                          |
|                                                                          |
|    $ tower new app                                                       |
|    $ cd app                                                              |
|    $ npm install                                                         |
|    $ tower generate scaffold post title:string body:text belongsTo:user  |
|    $ tower generate scaffold user email:string hasMany:posts             |
|    $ cake watch                                                          |
|    $ node server                                                         |
|                                                                          |
|  More info:                                                              |
|                                                                          |
|    IRC:      #towerjs                                                    |
|    Docs:     http://github.com/viatropos/tower/wiki                      |
|    Roadmap:  https://github.com/viatropos/tower/blob/master/ROADMAP.md   |
|                                                                          |
\--------------------------------------------------------------------------/
```

If you have heroku installed, it will also insert  this:

```
|  Deploy to Heroku:                                                       |
|                                                                          |
|    $ cake assets:bundle                                                  |
|    $ git init                                                            |
|    $ git add .                                                           |
|    $ git commit -a -m "first commit"                                     |
|    $ heroku create                                                       |
|    $ git push heroku master                                              |
```

If you don't have mongodb, coffee-script, or git installed it will say something like this at the top:

```
|  Please install git and mongodb before continuing:                       |
|                                                                          |
|    $ brew install git                                                    |
|    $ brew install mongodb                                                |
```

[todo] Add mappings for linux and windows on how to install these different things (it will just say install them w/o the instructions for now).

If you have node < 0.8, it will show a note in yellow saying you should update, if node < 0.6 then it will be in red saying it's unsupported:

```
|  Tower is installed!                                                     |
|                                                                          |
|  Note: You are using an unsupported version of node (v0.4.7).            |
|  Please upgrade to the latest version of node (>= v0.8.2).               |
|                                                                          |
|  Create an app:                                                          |
```

Any thoughts?