private Configuration getConfiguration() {
        if (conf == null) {
            conf = buildConfiguration(hdfsUri);
        }
        return conf;
    }
HDFS does not support some chars in its dir/filenames so need to clean
them here

@param path The path to clean
@return A cleaned path
stroom-pipeline/src/main/java/stroom/pipeline/writer/HDFSFileAppender.java