Add java5 generics to store#execute methods and callbacks

return (XWikiRCSNodeContent) executeRead(context, bTransaction, new HibernateCallback()
{
            public Object doInHibernate(Session session) throws HibernateException
            {
                ...
                return content;
            }
});

return executeRead(context, bTransaction, new HibernateCallback<XWikiRCSNodeContent>()
{
            public XWikiRCSNodeContent doInHibernate(Session session) throws HibernateException
            {
                ...
                return content;
            }
});