Option to post now working and showing result in a modal

- Included information about cross-domain requests in the README
- Organized the js a bit better, with a class
- Added a content-type to the html, removed js warning

refs #540
Update bootstrap to version 3.0.3

Version downloaded directly from http://getbootstrap.com
Includes several adjustments in the interface to make it look nicer with
this new bootstrap.