Removed bartMachine from MLRClassifier again because I failed to get it to work on my machine using MLRClassifier. BartMachine works fine if I start it from R, but there is a problem when running it from MLRClassifier, at least in my environment.

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@11288 e0a1b77d-ad91-4216-81b1-defd5f83fa92