Fix the usage error for config

Can't use 'self.config' to read the tempest.conf, change to use 'CONF'

Change-Id: I911a35ce90a9b65aa7bf1341e9f927e95049e074
Closes-bug: 1284500
Fix api_version filter for KeystoneV3AuthProvider

This add a missing '/' character during the replacement of api version.
Related to bp unit-tests

Change-Id: I83c2256c38ef91c9f36a564375a87f23bc8e0e25
Merge "Fix the usage error for config"
Merge "Fix api_version filter for KeystoneV3AuthProvider"