Add AMD, commonjs, browser global support. Add Package.json

I altered the header and footer to make the project run in various package loaders, and fallback to a browser global as before.

I also added a package json file so the project can be uploaded and used in some package loaders.

Lastly, I published the project to jam, as can be seen here: 

http://jamjs.org/packages/#/details/svg

If you want to publish to jam for in the future, just create an login, and I will put you as the maintainer. Thanks!