Fixed calendar admin screen style embedding if no Event Categories are defined.

The current logic only embeds the admin calendar styles if there are categories. I just pulled the style embedding logic out of that if block.

I also removed a stray double quote.

To reproduce:

Start with a fresh install or delete all categories.
Navigate to the Calendar Admin View
Result is an unstyled calendar.

Tested on WP 3.5.2 and Event Organiser 2.2.