standardize HelpText and Suites attribute handling in SavePropertiesResponder and SaveResponder
moved method setOrRemoveAttribute from SaveResponder and SavePropertiesResponder to PageData
fixed some warnings
New Test to show the difference between the way the default attributes are created with the constructor of PageData and when saved through SavePropertiesResponder
In PageData.initializeAttributes() only set the attributes, without a value
removed unnecessary argument that shadowed class attribute
Merge pull request #468 from ggramlich/normalize_params_xml

Use standardized PageData parameters to have less arbitrary changes in properties.xml
Few textual improvements in UserGuide.oneMinuteDescription.
Update release notes.