Add more support for external markdown.

Use en dash in title; <meta> is a void element.

move up presentation size section

This brings together all configuration options.

The 'grunt watch' command now also watches for changes to external
markdown.
The 'grunt package' command now packages all external markdown files for
rapid deployment in static enviroments.

Update location of multiplex demo server

Update README to include socket.io 1.3.5 examples