Various bug fixes for swift

only check if #dropdown hasClass drop-versions if a drop down is open. Otherwise it will never open the history drop-down

fix missing dir creation for file versions (OC_Filesystemview::mkdir doesn't work here because it doesn't create directories recursively)

fixed max possible upload size for files app in admin screen

A suggestion for simple, yet efficient variable interpolation in js translations

add parent directory to the file cache if it does not exist yet.