Support hmac with Faraday 0.9.0 forward

Requests get 403 failure with faraday 0.9.0
Faraday now normalizes request parameters via sorting by default but also
allows the params encoder to be configured by client.  It includes
Faraday::NestedParamsEncoder and Faraday::FlatParamsEncoder, but a 3rd party one can be provided.

Sigh. When computing the hmac, we need to normalize/sort the exact same way.
Find out which one is in use or select default, then use that for signing
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