The separation of acme4j-client and acme4j-utils was a design decision
that should avoid BouncyCastle to be a hard dependency of acme4j-client.
Anyhow acme4j is not really usable without BouncyCastle, so acme4j-utils
is used in almost all projects anyway.
This merge allows to extend the client API with some nice methods that
will make it easier to use.