attach handlers to document instead of filelist

@georgehrke This fixes all places where a #dropdown element is used. The calendar though performs differently: you have to click the submit button, to save changes, which is not what users might expect compared to the default sharing dropdown.

@jancborchardt maybe you have a mockup for how sharing in the calendar could use the same dropdown as files and gallery sharing?

also contains minor whitespace cleanups: don't for get to indent using tabs!