In case we pass a fully-specified URL to hscan, currently it will use as
is and that means the directory in which we want to save the status
files changes from what we mean. This patch changes hscan to replace all
slashes in the cluster name with underscores when generating the output
filenames.

This moves some data from README to the man pages and has other general
improvements.

This patch adds a man page for hscan and updates the README and other
man pages with the latest changes.