Update Jaxen to pull in a newer Xerces.
Not sure if this Jaxen dep is even used.
But anyway, 1.1.1 depends on Xerces 2.6.2, which lacks support for SAXParserFactory.setSchema.
That causes a baffling exception parsing changelog.xml:
java.lang.NullPointerException
	at org.apache.commons.digester.Digester.getXMLReader(Digester.java:1068)
	at org.apache.commons.digester.Digester.parse(Digester.java:1871)
	at hudson.scm.SubversionChangeLogParser.parse(SubversionChangeLogParser.java:76)
	at hudson.scm.SubversionChangeLogParser.parse(SubversionChangeLogParser.java:43)
	at hudson.model.AbstractBuild.calcChangeSet(AbstractBuild.java:916)
with the cause being sent to the log:
java.lang.UnsupportedOperationException: This parser does not support specification "null" version "null"
	at javax.xml.parsers.SAXParserFactory.setSchema(SAXParserFactory.java:419)
	at org.apache.commons.digester.Digester.getFactory(Digester.java:541)
	at org.apache.commons.digester.Digester.getParser(Digester.java:791)
	at org.apache.commons.digester.Digester.getXMLReader(Digester.java:1068)
Observable when using hpi:run to test a plugin,
since maven-hpi-plugin pulls in deps from maven-stapler-plugin and dumps them on the Jenkins classpath.