Adding key class tag extraction from checkpointed class;
adding assert to `DRM DFS i/o (local)` test to fail if key class tag is incorrectly loaded.

temporary commended h20 module since it doesn't compile
Merge branch 'MAHOUT-1615-drmFromHdfs' of http://github.com/dlyubimov/mahout into MAHOUT-1615
Read a sequence FILE not a directory- like the error says