TerminateAgreement endpoint

[jiivan]

fixes: #727

(just a branch name change from #792 to trigger market tests)

[nieznanysprawiciel]

I realized that we can't distinguish between Provider and Requestor Agreement in REST endpoints (like in GetAgreement), but here the problem is much bigger, because we have to know it, to fill terminator field in AgreementTerminatedEvent. But the way note, that we broke GetAgreement endpoint by adding AppSessionId.
I'm afraid we have to address these issues on specification level. @tworec

[nieznanysprawiciel]

This will be ugly log:
Some("Reason")
Maybe you should implement something like .display()

[nieznanysprawiciel]

signature is not optional for AgreementTerminatedEvent but this is part of #781

[nieznanysprawiciel]

Suggested change

	if let Some(s) = reason {
	Reason::from_json_reason(JsonReason {
	json: serde_json::from_str(s)?,
	})?;
	};
	if let Some(s) = reason {
	serde_json::from_str::<Reason>(s)?
	};

[nieznanysprawiciel]

Or even:

    Ok(if let Some(s) = reason {
        serde_json::from_str::<Reason>(s)?;
    })

[nieznanysprawiciel]

I would say it is even warn, because it would leave Provider and Requestor in inconsistent state

[nieznanysprawiciel]

Please don't display using debug if it is possible