Added plugin language files for Finnish language.

git-svn-id: https://plugins.svn.wordpress.org/appointment-booking-calendar/trunk@1040571 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added info about Finnish language.

git-svn-id: https://plugins.svn.wordpress.org/appointment-booking-calendar/trunk@1040651 b8457f37-d9ea-0310-8a92-e5e31aec5664