Use jsonutils to load adapter response

This is not technically needed, however we and the libraries we use,
aren't very good about keeping our strings and bytes straight for python
3. jsonutils has an attempt to decode stage that means we can let it
manage the correct types.

Change-Id: I2caf4a5b9a04495aa0286f2b6e3193a17ff246e5
Merge "Use jsonutils to load adapter response"