Add main property to package.json
Change CJS definition to require vex.js with relative path

With this change we can require() with a package relative path like this: 
var dialog = require('vex/js/vex.dialog.js')
add repository property to avoid npm warning
Change CJS definition to require vex.js with relative path

    With this change we can require() with a package relative path like this:
    var dialog = require('vex/js/vex.dialog.js')
grunt build
Merge pull request #71 from hugomrdias/browserify

Support CommonJS and browserify