Not by default whonix-workstation-extra-applications clarification

Clarified that whonix-workstation-extra-applications does not get install by default.
Merge pull request #129 from kenkes/patch-1

improved whonix-workstation-extra-applications package description
fix, chmod -x whonix_shared/usr/share/whonix/icons/whonix.png
debian/whonix-shared-files.postinst: removed init script hack, now using proper init script dependencies
Merge remote-tracking branch 'origin/master'