add python-all for build

Signed-off-by: Mike Marchetti <mmarchetti@sandvine.com>
diff --git a/Dockerfile b/Dockerfile
index b81e0da..80718ed 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 FROM ubuntu:16.04
 
-RUN apt-get update && apt-get -y install git make python3 \
+RUN apt-get update && apt-get -y install git make python python3 \
     libcurl4-gnutls-dev libgnutls-dev tox python3-dev \
-    debhelper python3-setuptools python3-all apt-utils
+    debhelper python3-setuptools python-all python3-all apt-utils