Added Composer support and license file

This patch adds a composer.json file for use with Composer and Packagist. Also adds the missing LICENSE.txt file.

Sample interim configuration (the "repositories" key can be removed once the library is up on Packagist):

```
{
    "repositories": [
        {
            "type": "vcs",
            "url": "https://github.com/dotink/Parody"
        }
    ],
    "require": {
        "dotink/parody": "dev-master"
    }
}
```