The `grunt css-themes` command now loops through all Sass files. There is no need to add the newly created file to the task list.

The alignment information were already in the generated html.
The css was the only thing missing, so I added it.

move the slide-number out of the controls to a proper position and little fix to the updating event.

the *.min.js didn't chaged yet.

Closes #662.

css/theme/template/settings.scss adds the $headingMargin variable, set to `0 0 20px 0`.
css/theme/template/theme.scss uses $headingMargin to set margin on headers.

They looked a little wonky if you used a G or a Y.

The Serif theme was a little flaky previously