This patch migrates rest_client module to tempest-lib from tempest.
The latest Change-Ids of each file are the following when this migration:
* common/http.py : I43703e2289212389c7841f44691ae7849ed1f505
* common/rest_client.py : Ie9105b5d01e7883213c1d3398cc5fe56782920d9
* common/utils/misc.py : I9a591eaa1cf4dabba58f06a64814611a05a51365
* exceptions.py : Ic8fc216377942619f11a2462b79d0597071ac294
* tests/base.py : I8f14cd2ca6afc38d3fe8ee758272071111022896
* tests/fake_auth_provider.py: Id12341de52204e2c428e10b4b758b700b0fbab09
* tests/fake_http.py : I8f14cd2ca6afc38d3fe8ee758272071111022896
* tests/test_rest_client.py : Ie9105b5d01e7883213c1d3398cc5fe56782920d9
NOTE: Some docstrings are changed to avoid H404 and H405.
Change-Id: I879a02681c99376ae57458a0f7a04c8032dfebb2