This is a regression against EAP 8.0, so priority is a blocker

Steps to reproduce:

• echo "random string, definitely not valid provisioning.xml" > /tmp/provisioning.xml
• ./jboss-eap-installation-manager-8.1/bin/jboss-eap-installation-manager.sh install --dir=/tmp/tmpServer --definition=/tmp/provisioning.xml --channels=/path/to/jboss-eap-8.1/.installation/installer-channels.yaml
• See output:

  
  ERROR: org.jboss.galleon.ProvisioningException: javax.xml.stream.XMLStreamException: ParseError at [row,col]:[1,1]
  Message: Content is not allowed in prolog.
  

Tool should print user-friendly error message, not part of java exception. In EAP 8, prospero prints this error message: "Failed to parse provisioning configuration: " + provisionignXmlPath.

cc jkasik@redhat.com