Fix servers selection in server and specification

[brylie]

@huksley asked the following in PR #20:

Any way to fix servers entry which is generated as empty now?

Task

Determine if/how to set the server value in the specification or documentation UI. Is this something that Connexion can do automatically? Can this be done in a way that is deployment agnostic?

[huksley]

Not OP's fault :)
spec-first/connexion#1139