MAHOUT-833: Make conversion to sequence files map-reduce - fixed issue with not reading a directory list

git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1496078 13f79535-47bb-0310-9956-ffa450edef68
MAHOUT-944: lucene2seq - more code cleanup, removed unused imports

git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1496123 13f79535-47bb-0310-9956-ffa450edef68