Improve HTML templates of 'parties' and 'clock' examples

* Change double quotes to single quotes inside ```class``` tags in parties example
* Don't split ```line```, ```circle``` and ```svg``` tags in clock example

The reason behind these changes is to make it simpler to process templates' code when it's getting converted to, say, JADE. I've tried many different HTML pre-processors, and none of them liked split ```style``` tag attributes. Also double quotes inside double quotes without escaping is certainly something that is broken, and even GitHub's syntax highlighter doesn't like it.