Remove migrated utils code

This commit removes all the utils code which has been migrated to
tempest-lib and updates the uses of it to point to the library instead.

Change-Id: I9207641aa91c0ea7feb8e067316fc220880c3a3b
diff --git a/requirements.txt b/requirements.txt
index 4690329..b14af9d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -24,4 +24,4 @@
 iso8601>=0.1.9
 fixtures>=0.3.14
 testscenarios>=0.4
-tempest-lib>=0.2.0
+tempest-lib>=0.3.0