Use standardized PageData parameters to have less arbitrary changes in properties.xml

The properties.xml files were changing several times, depending on the way they were saved.
This was quite annoying, when reviewing the changes before commiting to the source control.
I identified three different cases:
- New files: the boolean attributes contained a "true" value
- After editing the page: the boolean attributes contained no value, but were just set or removed. The Help and Suites attributes were not set, when no value was entered
- After editing the properties: the boolean attributes contained no value, but were just set or removed. The Help and Suites attributes were set with an empty value, when no value was entered

This pull request standardizes the behavior to the old "After editing the page" case:
The boolean attributes contain no value, but are just set or removed. The Help and Suites attributes are not set, when no value is available.