The Client used to start its own listener and http server, so it could
receive the Server's challenge. However, that design does not work when
the Client must be used in an application that is already an http(s)
server.
Therefore, this change adds a Handler method to the Client, that returns
the Client's handler, as well as the pattern it should registered for
with an HTTPS server. This means, it is now the responsibility of the
caller to setup the listener for the Client before the Challenge can be
started.
Change-Id: I160e21c470322f7acad209ac28a15eaeed36c2c4
A demo client and server are included, to help with testing.
TODO(mpl): restrict IP space
Issue #722
Change-Id: I6952069e8885c06adcbb8fca103af9d83f2fa9a7
mpl