Fix pep8 issues (#3)

Fixing:
* import orders
* importing decorators module instead of idempotent_id function and using as @decorators.idempotent_id
* docstrings
diff --git a/tox.ini b/tox.ini
index 322017c..e3d3ee0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -96,7 +96,7 @@
 # multiline doc strings just don't have a natural summary
 # line. Rejecting code for this reason is wrong.
 builtins = _
-exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
+exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build,tungsten_tempest_plugin/services/contrail/json/
 
 [hacking]
 local-check-factory = tungsten_tempest_plugin.hacking.checks.factory