Fix submission of 'xsd:date' type fields
 -include a property value's expected type as RDFa 'datatype' attribute
 - include object's datatype when locally constructing triples
 - only create an 'old triple' if the old value is not 'undefined'
 - add method podd.buildTriple()
 - add method podd.getPropertyRange()
 - rename addShortTextBlurHandler() to addTextFieldBlurHandler()