Inject and use Ripple in any web browser (without a browser extension)

See commits for details, as this also has a few commits that cleanup some things and fix a bug or two. 

While this has been tested _alot_ by me, I think this still needs some solid review, and comments, etc would be greatly appreciated.

Also, here is the ASF mailing list thread about this feature (i.e. "Hosted Ripple"): http://markmail.org/message/yfoavio4ffdgfmmy

PS If anyone has a major thing to discuss that is not code review based (about the features in this PR), etc, please reply on the public mailing list about it. :-)