Send swift upload instructions to workers

Have zuul send signed credentials as part of the job for workers to
consume and upload assets to a defined location.

Zuul currently doesn't care about logs however this change will
suggest a LOG_PATH to builders as a unqiue destination prefix
allowing zuul to know preemptively the destination.
The workers are still required to send a URL of the final location.

Change-Id: I042cdd2dd2407f381cafcabc5c6b83d9b9a9eb00
diff --git a/requirements.txt b/requirements.txt
index f14441b..bb48290 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -14,3 +14,5 @@
 voluptuous>=0.7
 gear>=0.5.4,<1.0.0
 apscheduler>=2.1.1,<3.0
+python-swiftclient>=1.6
+python-keystoneclient>=0.4.2