On the various pieces, I think:
0.20: -0 for removing the deprecation, +1 for improving the
deprecation message with links to the corresponding class.
0.21: new core api should be stable except for Job and Cluster
new library code should be evolving
-1 for removing the deprecation, we need to
0.22: all of the new api should be stable and the old api deprecated.
> Currently there is almost no way to write a moderately complex MR job that
> doesn't spew deprecation warnings.
That is false in 0.21.
-- Owen
