Travis CI support added (python 3.6, 3.7, 3.8).

.travis.yml

@@ -0,0 +1,15 @@
+language: python
+
+dist: bionic
+
+python:
+  - "3.6"
+  - "3.7"
+  - "3.8"
+
+
+install:
+  - pipenv install
+
+script:
+  - pytest