Optimize Docker image footprint

Rebase to python:2-slim
Remove unused pip packages

Change-Id: Idc9dfdc11d4792a63c7c144587c13705e87bb4bc
Issue-ID: MULTICLOUD-505
Signed-off-by: Bin Yang <bin.yang@windriver.com>
diff --git a/multivimbroker/test-requirements.txt b/multivimbroker/test-requirements.txt
new file mode 100644
index 0000000..e39b30b
--- /dev/null
+++ b/multivimbroker/test-requirements.txt
@@ -0,0 +1,5 @@
+# for unit test
+django-nose>=1.4.0
+coverage==4.2
+mock==2.0.0
+unittest_xml_reporting==1.12.0