Add a package.json npm manifest to root

[wkonderla]

Basically something like:

{
"name" : "validity",
"version" : "1.4.6",
"author" : "whatgoodisaroad",
"description" : "Custom Client-Side Validation with jQuery",
"homepage" : "https://github.com/whatgoodisaroad/validity",
"license" : "Public Domain",
"keywords" : ["validity", "client", "jquery"],
"repository" : {
"type": "git",
"url": "git://github.com/whatgoodisaroad/validity.git"
},
"main" : "./build/jquery.validity.js",
"files" : ["build/*", "README.md"]
}