Add configuration for auto discovery of kingbird Tempest testcases.
Restructure and fixed minor issues in existing tempest.
Added README.rst for the steps to run Kingbird tempest plugin.
The configurations which are specific to kingbird
plugin are in kingbird/tests/tempest/scenario/config.py and
currently the default configuration is used from here.
Change-Id: I1b652c82beea61d84b3f42bf657925b1571f7a8d