Was not closing the MultipleOutput instance after writing data chunks

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@10106 e0a1b77d-ad91-4216-81b1-defd5f83fa92
Fixed a bug where hdfs:// would be prepended twice to the URL used to write evaluation arff and csv files in some cases

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@10107 e0a1b77d-ad91-4216-81b1-defd5f83fa92