Support for multiple authentication methods; Adding more images, reworking large images.

1. Added INPUT id="provider" and INPUT id="method" so that the server side can now authenticate via OAuth2 and custom protocols implemented by some providers. See https://github.com/frgomes/velruse for more info about this. NOTE: this was implemented only on openid-jquery.js !

2. Reworking several large images, making sure the maximum 90x30 is respected and reducing file sizes when possible without compromising quality. I've also added some more icons for Windows Live, Github and bitbucket.

3. Adding new entries to openid-en.js and fixing existing ones which were not "compiling". Now two rows with small icons are displayed.

5. Fixing .css file so that highlighting when multiple rows are displayed does not break the layout anymore.