Fix deprecated dtd url and create-hibernate-cfg-xml script

Fixes:

grails create-hibernate-cfg-xml
Error executing script CreateHibernateCfgXml: No such property: hibernatePluginDir for class: CreateHibernateCfgXml

grails run-app
WARN [localhost-startStop-1] org.hibernate.internal.util.xml.DTDEntityResolver - DTDEntityResolver.java 75 - HHH000223: Recognized obsolete hibernate namespace http://hibernate.sourceforge.net/. Use namespace http://www.hibernate.org/dtd/ instead. Refer to Hibernate 3.6 Migration Guide!