Remove HttpClientWrapper as GzipHttpClient is a superset of its function...

Remove HttpClientWrapper as GzipHttpClient is a superset of its functionality
and it is code duplication

Things to consider:
Since there's only one HttpClientWrapper implementation left, it may be better to call it "HttpClientWrapper" not GzipHttpClient as the use of gzip isn't a differentiator any more.

*edit* dotCom appears to be using and wrapping GzipHttpClient (see DotComHttpClient.cs) though this appears to be a an IoC default not an explicit choice. It looks like no impact to dotCom from this Pull Request.