Partial sync with OpenStack requirements.

Where we're using the same libraries as OpenStack, sync with the
OpenStack versions. Just to be nice.

Change-Id: I8e90d2a8945d62e962b813c6396f0e7db4e14222
diff --git a/requirements.txt b/requirements.txt
index 0481dcc..7b43b96 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,13 +1,13 @@
 pbr>=0.5.21,<1.0
 
 argparse
-PyYAML
 python-jenkins
+PyYAML>=3.1.0
 Paste
-WebOb
-paramiko
+WebOb>=1.2.3,<1.3
+paramiko>=1.8.0
 GitPython>=0.3.2.RC1
-lockfile
+lockfile>=0.8
 ordereddict
 python-daemon
 extras