This release adds support for Python 3, a new "-H" option for specifying
hosts one-by-one instead of (or in addition to) using a hosts file, new
"-x" and "-X" options for passing extra commandline arguments to ssh and
rsync, a "-S" option to prsync for the special case of passing extra
arguments to ssh, and a new "-I" option for specifying that pssh should
read from standard input.
