Add a test with parallel GLM x-validation.

Also drop the "expand cat" flag.
Fix GLM model bug; fix Job block bug.

Job.get() now does proper blocking; Job.start() takes a F/J task to
block on.  GLMGrid also should not lose a thread blocking.  RF also
should not lose a thread blocking.

New C.C. arch requires an extra reduce step into an empty object,
generally requires reduce steps to assign all fields.
Remove no-longer-correct assert