fix utf8 filenames in ie download response header according to rfc5987, see http://stackoverflow.com/questions/93551/how-to-encode-the-filename-parameter-of-content-disposition-header-in-http

cleaning up the settings. standardize the format, add missing I10N and other small things. Yes. This is not perfect. But way better than before ;-)

https://github.com/owncloud/core/issues/557