Version 1.8 released

Proudly announcing the new release 1.8 which contains these features, enhancements,
bugfixes and changes.

- feature: filtering via TabViews for vintage, category and other attributes
- feature: empty storages are separated from non-empty storages (via TabView)

- bugfix: display correct messages for empty cellar
- bugfix: sorting by name works again (accidently removed)

- enhancement: exporting is done in background (service)
- enhancement: standard menu icons are used (according to style guide)
- enhancement: attributes note, rating and region can be disabled for editing
in settings (feature request from user weinakademiker)

- changed: search is working now context sensitive
- changed: using default android theme (which means black blackground)

Enjoy!