add: demo server and client

demo_server/.travis.yml

@@ -0,0 +1,14 @@
+# ref: https://docs.travis-ci.com/user/languages/python
+language: python
+python:
+  - "3.2"
+  - "3.3"
+  - "3.4"
+  - "3.5"
+  - "3.6"
+  - "3.7"
+  - "3.8"
+# command to install dependencies
+install: "pip install -r requirements.txt"
+# command to run tests
+script: nosetests