Log Message:
Update shared-mime-info to 1.6.

shared-mime-info 1.6 (2016-02-23)
* Add XAR archive mime-type
* Add GeoJSON mime-type
* Add GPX mime-type
* Add xdg-app mime-type
* Add *.xht glob and magic for XHTML files
* Bump priority of archive mime-types with long magics,
  to avoid false positives when detecting files inside
  the archive itself