Add style hooks for date/time components.

Adds css styles to each flydown in date and time entries. Makes entries
much easier to style.
Make SwatFlydown's warpper inherit CSS classes.

Classes are pulled up from the flydown except for the swat-flydown
class. The swat-flydown-wrapper class is still added.
Merge pull request #3 from gauthierm/swat-date-entry-style-hooks

Add style hooks for date/time components.