Allow enabling http_wire_trace via env vars

[eXpire163]

Hi,

i'm not a ruby dev but we are using awspec. Now we have moved the execution to aws and facing wired connection issues:

1) iam_role 'DatabaseAdmin' is expected to exist
     Failure/Error: it { should exist }
     
     Seahorse::Client::NetworkingError:
       Failed to open TCP connection to : (getaddrinfo: Name does not resolve)
     # ./spec/rds_spec.rb:4:in `block (2 levels) in <top (required)>'

The wired thing is that it does not show a target where it tries to connect to. The other thing is that we can run aws iam list-roleswithout a problem through the proxy setup in env -> http-proxy / https-proxy

[k1LoW]

@eXpire163 Thank you!!!

[k1LoW]

Released as v1.22.1.