Test case for #55, is passing.
Proper failing test case for #55

1) The API sends a Content-Type: application/json body with no header.

2) The response handler in faraday tries to parse the body response for a HEAD
request.

Time to compensate.
Error parser checks body even with JSON type
Merge branch 'mattly/55-client-ping-raises-correctly-on-error'
bump to 0.6.3, release notes