Add hacking rule to enfore no config in tempest.lib

This commit adds a hacking rule to enforce that we never add a config
dependency on tempest/lib. Right now we're completely dependent on
reviewers catching this, it is a strong rule so we should ensure we
can't ever land a change that does this.

Change-Id: I1ab1ba52573c6706a50abcd021759c93dd19aa44
diff --git a/HACKING.rst b/HACKING.rst
index b66fa24..0f8a563 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -21,6 +21,7 @@
 - [T111] Check that service client names of DELETE should be consistent
 - [T112] Check that tempest.lib should not import local tempest code
 - [T113] Check that tests use data_utils.rand_uuid() instead of uuid.uuid4()
+- [T114] Check that tempest.lib does not use tempest config
 - [N322] Method's default argument shouldn't be mutable
 
 Test Data/Configuration