Schematron from ant doesn't respect class path definitions for file

[tgraham-antenna]

Moved from Schematron/schematron#13

What steps will reproduce the problem?
1. Running the schematron task without saxon defined in the system classpath

See 
http://stackoverflow.com/questions/23132201/setting-ant-classpath-in-build-xml 
for someone [else]'s description of and proposed solution to the problem.

This is an issue when you can't define the classpath for saxon ahead of running 
an ant script.