Fixed CI configurations for pull request #11. Removed Python 3.3 build and added new versions. (#13)

Author: liboyue

.travis.yml

@@ -2,11 +2,15 @@ language: python
 
 python:
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
-  - "3.6-dev" # 3.6 development branch
+  - "3.6"
+  - "3.7"
+  - "3.8"
+  - "3.8-dev"
 
-install: "pip install ."
+install:
+  - pip install .
 
-script: py.test
+script:
+  - pytest