Pin python-daemon<2.0

The latest release is missing a dependency.

Change-Id: Ia935a1a04a201fb39c134a13bf512dc776dea278
diff --git a/requirements.txt b/requirements.txt
index 97ec161..1788b85 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,7 +5,7 @@
 argparse
 
 lockfile
-python-daemon
+python-daemon<2.0
 extras
 GitPython>=0.3.2.RC1
 sphinxcontrib-programoutput