Added test coverage for $.Mustache.addFromDom()

Patched up issue around raising erros for missing named templates.

Simplified selector for target script elements.

Raised version to 0.2.5.
Fix for Github Issue #13 (addFromDom selector)

The addFromDom method's jQuery selector required the templates to be
children of the <html /> element, when the documentation specified they
could be loaded anywhere on the DOM.  Modified selector and added unit
test to ensure that's the case :)

Thanks for the bug report, @VinceG3