Disabled transport encoding to okta to prevent EOF

[drewblas]

Our users would get constant "unexpected EOF" errors when trying to authenticate with 2FA against okta.

We traced the cause to trying to decode the transport encoding (gzip) on the chunked body stream in the response.

This causes ReadAll to return an io.EOF err even when it should not:

aws-okta/lib/okta.go

Line 516 in b1140c3

rawData, err = ioutil.ReadAll(res.Body)

The fix that has worked is to add a header to prevent okta from encoding the response.

[nickatsegment]

Made a quick comment edit. I'm going on faith that this does what it says and doesn't cause a performance impact.