Bugfix: Align href URL encoding with oc10

We now use the same percent encoding for URLs in WebDAV href properties as ownCloud 10.

https://github.com/cs3org/reva/pull/1425
https://github.com/cs3org/reva/pull/1472
https://github.com/owncloud/ocis/issues/1120
https://github.com/owncloud/ocis/issues/1296
https://github.com/owncloud/ocis/issues/1307
