add awscli to arm Dockerfile

Signed-off-by: Victor Vieux <vieux@docker.com>

Dockerfile.armhf

@@ -46,7 +46,8 @@ RUN apt-get update && apt-get install -y \
 	python-websocket \
 	xfsprogs \
 	tar \
-	--no-install-recommends
+	--no-install-recommends \
+	&& pip install awscli==1.10.15
 
 # Get lvm2 source for compiling statically
 ENV LVM2_VERSION 2.02.103