Merge pull request #148 from tianhao64/master

update python test versions

Author: tianhao64

.travis.yml

@@ -1,12 +1,12 @@
 language: python
 python:
-  - "2.7.13"
+  - "2.7"
   - "3.6"
 # command to install dependencies
-install: 
+install:
   - pip install -r requirements.txt --extra-index-url file://$PWD/lib --upgrade  --ignore-installed six
   - pip install -r test-requirements.txt
 # command to run tests
-script: pycodestyle samples tests
-script: pytest
-
+script:
+  - pycodestyle samples tests
+  - pytest