Merge branch 'feature/install-wizard-6136'

refs #6136
Add wizard page for the logging configuration

resolves #6129
Update Vagrant Icinga 2 test config

refs #6127
Fix problems with the Puppet manifest when PostgreSQL's default encoding isn't UTF-8

fixes #6211
Multistep pages should have the possibility to add additional submit btns

refs #6136
Multistep page names should not be set implicitly on instantiation

refs #6136
Add placeholders for our wizard pages

refs #6136
Fix that Form::reset() does not clear sub forms as well
Multistep page configurations need not to be writable

refs #6136