Excitingly, DTask copyOver was backwards

Exception-dropping much?  Mostly means MRTask2 w/ distributed-exceptions
could (sometimes) silently drop them.
Tweak parser header/col detector

When 1st 10 rows show different column counts, if the 1st line is also
the longest - take that as the number of cols, else take the col-count
that occurs most often.
Theory is the 1st line is a header, and all cols have a label even if
some later cols are missing
Merge branch 'master' of github.com:0xdata/h2o