fix javascript issue (links in settings not clickable)

load jqueryui before jquery.multiselect.min.js

fixes:
Uncaught TypeError: Object function (e,t){return new v.fn.init(e,t,n)} has no method 'widget' jquery.multiselect.min.js:20
Uncaught TypeError: Object [object Object] has no method 'multiselect' vacation_sieve.js:31
fix PHP 5.3 incompatibility issues
availability to overwrite vacation_subject and vacation_message in config
css: load vacation_sieve.css only for larry skin (fix broken classic
skin)
Merge pull request #9 from pevik/master

Fixed bugs and usability