add mustache template support

- header-template finished
- footer-template finished
add a mustache-file-render function

mustache-file-render is a shortcut function inspired by django
render_to_response function, it will render a file with a hashtable
context and then returns a string.
add recursive mustache rendering support
add a simple template loader
add a new theme based on twitter bootstrap

- add a simple footer
- add a sidebar for table-of-contents
- make bootstrap theme work with mustache