Prepare for publish to npm

[shaungrady]

Resolves #37

Few things to be aware of:

• Capital letters are not permissible in the name field of the package, so I changed it to media-check.
• Your script is not a CommonJS module, so it won't be easilyrequireable. If/when you do decide to make it CJS-compatible, it will have to be bundled for testing.
• The files field in package.json defines what files are included when someone npm installs mediaCheck. The minified version is not included in the package, as this is discouraged by npm.

@robtarr Let me know if you have any questions. Otherwise, it's ready for merge and npm publish.

[robtarr]

Yeah, I don't want to publish it to NPM before the work to convert it to a module is done. I'll open another issue for that if I can't get to it soon.

Thanks.