pep8
introduce installation option adhocracy.readonly
create check.readonly
block any modifications in readonly
create warning message
fix user delete
fix proposal edit badges auth check
fix comment auth
fix user badges
don't show feedback button if feedback is not possible
fix 'show profile' in navigation
Revert "fix comment auth"

This reverts commit a7298a5cb50602de4079ae7f7797e79fa7880972.
Merge pull request #644 from xi/feature-622-freeze-installation

readonly installation