Allow a user to enable certificate pinning when verifying a TLS connection to a nexpose console

[bcook-r7]

What I would like is, given an initial connection to a Nexpose console with a self-signed certificate, being able to cache that certificate at the client level, then verify later that this is the same nexpose console as before. This would be similar to the known_hosts file in ssh, which allows one to know if there is a MitM attack and act accordingly (terminating the connection).

[gschneider-r7]

I made a proof-of-concept implementation of this a couple years ago, but never got around to making it comfortably usable in the gem. You can see that here: https://gist.github.com/gschneider-r7/52499ab8c21aace0f8d3

@bcook-r7 suggested:

Maybe the user could specify a block that contains the certificate lookup / save callbacks, leaving the underlying implementation to the gem user. Thus nexpose-client would just supply hooks.

[gschneider-r7]

Resolved with #254 and released in v5.3.0. Additional documentation on the wiki page.

[busterb]

Thanks @gschneider-r7 !