Comment 19 for bug 1330132

As Kopec mentioned in his comment, below tempest file still using the 'Member' role and that can be replaced with 'member' role.

tempest/config.py
- 'Member' is used as default value of operator_role config option we can change it to 'member'.

tempest/lib/common/dynamic_creds.py
- here it is used to make sure if no roles are configured then at least one role is assigned to
user by default so replacing 'Member' to 'member' is fine here.

tempest/tests/lib/common/test_dynamic_creds.py
- this can be replace with 'member' when changing the dynamic_creds.py

etc/tempest.conf.sample
this is same when changing the tmepest.conf