reenable full request/response logging at DEBUG

For the difficult bugs we are often missing information if we don't
have the full request / response traffic. Provide a new
_log_request_full which functions at a debug level and provides
this. Pretty print the bodies for resp and req for readability.

Change-Id: Ic1f7f324c04fc2d2529c7065b0dcda1640d4fb53
Merge "reenable full request/response logging at DEBUG"