updating Mocha, and related files

Updating mocha & sinon libraries, to current versions. Also bringing runtest.html into step with the libraries used in the Sinatra page layout (DOCTYPE added to stop IE dropping into Quirks mode).

Gives the same results as the previous version - however there do appear to be some oddities.

Some of the test seem to end in a pending state.

The new version of mocha adds links to pull out individual tests. When this is done the plugin test 'should render a plugin' produces an error, only spotted as it produces an error with IE9. As the current version gives the same result, see http://fed.wiki.org/runtests.html?grep=plugin. The attributes are just in a different order, so guess this is not a problem.
```
Error: expected 
'<p>blah <a class="internal" title="view" href="/link.html" data-page-name="link">Link</a> asdf</p>'
to equal 
'<p>blah <a class="internal" href="/link.html" data-page-name="link" title="view">Link</a> asdf</p>'
```