Improve scripting support for HST content beans

To support to use beans and compounds in jsp and ftl that do not have a specific java hst content bean for them (with @Node(jcrType=myproject:somedocument)), we need some simple extra getters next to the already existing
org.hippoecm.hst.content.beans.standard.HippoBean#getProperty() that returns a Map<String, Object>