chore: Basics for CHANGELOG.md, CONTRIBUTORS, and npm scripts for outdat...

...ed and shrinkwrap

Fixes #11 
Fixes #13 
We could also use something like [grunt-shell](https://github.com/sindresorhus/grunt-shell) if we want to move these commands out of the package.json and into the Gruntfile.js:

```js
module.exports = function (grunt) {
  'use strict';

  require('load-grunt-tasks')(grunt);

  grunt.initConfig({
    shell: {
      outdated: {
        command: 'npm outdated --depth 0'
      },
      shrinkwrap: {
        command: 'npm shrinkwrap --dev'
      },
      'audit-shrinkwrap': {
        command: 'nsp audit-shrinkwrap || true'
      }
    }
  });
};
```

Then to call the commands we use something like `grunt shell:shrinkwrap` (or it can be combined with other grunt tasks).