OC.Share icons now operate on fileList instance

Since OC.Share needs the current directory to operate on, it now accepts
a fileList instance.

To make the fileList instance available, it is now passed as data
argument to the "fileActionsReady" action.
Fix OC.Share.updateIcon when more than one list in DOM

When there is more than one file list in the DOM, the updateIcon()
method needs to update the icons of each list respectively (as a
temporary solution until we can make it dependent on the list itself
without major changes)
Fix detection whether path is defined in file info