simplify rest_client logging

this takes the rest client req/resp down to a single short info
line per call. This eliminates the issue where the multiline output
is interleaved between many testr process, thus confusing. It
should be a pretty concise view of the rest calls being made from
tempest.

It removes parameters that were previously used for debug. We'll
incrementally add these back if this was too much removal.

Change-Id: I342483e2a3c1396537df1fab825ebef8a7e75101
Merge "simplify rest_client logging"