[Fixes #1429] Content negotiation does a case-sensitive matching of media type's parameter values

@harshgMSFT 
I am guessing you meant `GetStringAsync` instead?...sure, I could use that...

Ideally I would like to log the response details(headers and body) when the response is not of an expected status code  and body, but I *think* we are not following this approach in our functional tests?...this should give us enough information for doing quick analysis before deep diving into the failure...