Adds a -p option to swift-dispersion-report that will output the
partitions missing copies to standard error. Another thing we've been
meaning to add for forever. It's useful when you want to do some
further research on whether a partition truly has fewer copies or if
they're just somewhere else in the cluster due to a ring change, for
instance.
DocImpact
Change-Id: I5e47aa5818483ecc34b39ef6f8cd83ad312ed9a0
dcc89e3ad6