Dredd is not using just the 1st req-res pair within APIB transaction examples

[honzajavorek]

There is a problem introduced with migration to API Elements in order to support Swagger in Dredd. Original implementation always selected the first request-response pair from each transaction example. This wasn't re-implemented correctly on top of API Elements. Instead, all specified responses are appearing, which breaks Dredd's behavior in many ways. Respective test was ported, but unfortunately with the same mistake.

Some early adopters (cc @philsturgeon) discovered the issue and considered it to be a new feature, but it really breaks how Dredd should work at the moment and needs to be removed 😞 It leads to duplicate transaction names and other undefined behavior.

In order to implement #25 and #78, which many believed happened when they discovered the bug, much more work needs to be done. Namely designing and adopting a new way of addressing transactions in Dredd #227.

Fix is on its way in apiaryio/dredd-transactions#61 This issue is labeled as "behavior change" since it is behavior change for those who already upgraded, but in fact it's a regression fix, i.e. return of the previous behavior. To communicate this change, Dredd's major version will be bumped.