Content-Types - binary Accept header and v1 JSON type

[harmanpa]

The client was previously changed to only support deserializing application/vnd.onshape.v2+json Content-Types, however application/vnd.onshape.v1+json is still used as a header for some responses, notably empty responses from delete methods. Both should be considered.

The client currently uses an Accept header of application/vnd.onshape.v2+octet-stream for download responses, however some methods such as PartStudios.exportParasolid() now give a 406 response to this.