Add tests for new Python versions (#10)

* Add tests for new Python versions

Author: chaosmail

.travis.yml

@@ -7,6 +7,10 @@ python:
   - "3.3"
   - "3.4"
   - "3.5"
+  - "3.6"
+  - "3.7"
+  - "3.8"
+  - "3.9"
 
 # command to install dependencies
 before_script:
@@ -25,4 +29,5 @@ after_success: coveralls
 
 branches:
   only:
-    - master
+    - master
+    - /.*/