Fix HttpClient change which broke multicloud

Fix HttpClient change which broke multicloud

The lines added to HttpClient in https://gerrit.onap.org/r/#/c/72771/
broke the usage of HttpClient by the multicloud adapter.

The 'content-type' line seems redundant - content type is specified
in the HttpClient constructor.

The 'Authorization' line (which broke multicloud usage) seems
inappropriate here.  The Authorization string shouldn't be
hard coded into a generic client.  There are other methods
available for adding the authentication header.

Change-Id: I19ac1a382778fe50bc7e98e1e9b9a4d84897b2a6
Issue-ID: SO-1257
Signed-off-by: Eric Multanen <eric.w.multanen@intel.com>