Added support for more than two class exclusions

• Thanks to @mariomc for the fix if there is more than two classes to exclude and to @bramvandenbussche and @lamigue for also spotting it
• Stopped running through class checking if element clicked on has no classes or id's to improve performance
• Updated README
• Published latest repo with main.js to npm to allow webpack usage
• Added file input type to example to show functionality
• Updated readme detailing excluding element that directive is on