Added title, time and date support for the template.

Hi.

I've added a bit of customization abilities to the template, by adding `templateOptions` section, that should provide a bit (not too much) more control for how the HTML content is created out of MD.

The added parts include:

- time and date formatting options (following grunt's built-in format - node-dateformat)
- usage of alternative title or first MD line as title (removing # if there)
- ability to add author into the resulting HTML

Hope this helps, but in any case, I've added a larger explanation to the README.