Added info about Danish language.

git-svn-id: https://plugins.svn.wordpress.org/booking-calendar-contact-form/trunk@1039508 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added plugin language files for Danish language.

git-svn-id: https://plugins.svn.wordpress.org/booking-calendar-contact-form/trunk@1039509 b8457f37-d9ea-0310-8a92-e5e31aec5664