IDE-932

Fix cannot open new portlet wizard bug;
Make sure to only show available superclasses
in the dropdown list after switching projects.
IDE-919

Add validation for namespace element and package-path
attribute in service builder descriptor and new service
builder wizard;
Fix some NullPointerExceptions for liferay descriptors
when switch severity level to ignore.
IDE-946

Add liferay-portlet.xml validation for latest
class element changes and sort them.