On OpenWrt nc (netcat) connectivity test makes more sense than
ping because a) for non-root users ping is not permitted, and
b) nc is a default binary included with OpenWrt.
We do, however, have to change the upstream default from using
`nc -vz` to `printf "<http head request>"|nc` (with openwrt
nc if text is sent then nc closes after a response and fails
if no connection is made; the response is already thrown away
(to /dev/null) by the existing code).

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>

The project has been revived upstream and a user has convinced me
there is a valid use case for this package in openwrt, so remove
deprecation notice, adjust links to upstream (it's moved) and
update to latest version.  Sync behavior with that expected upstream.

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>