Use matrix feature from travis CI

.travis.yml

@@ -1,7 +1,12 @@
-language: python
-python:
-  - "3.6"
-services:
-  - docker
-script:
-  - ./test.sh
+matrix:
+  include:
+    - language: python
+      python:
+        - "3.4"
+        - "3.7"
+      before_script:
+        - cd cli
+      install:
+        - pip install -r requirements.txt -r test-requirements.txt
+      script:
+        - python -m unittest discover

cli/tox.ini

@@ -1,21 +0,0 @@
-[tox]
-skipsdist = True
-envlist = pep8,py2,py3
-
-[testenv]
-deps = -r{toxinidir}/requirements.txt
-       -r{toxinidir}/test-requirements.txt
-install_command = pip install -U {packages}
-commands = pytest -v {posargs: tests}
-whitelist_externals = sh
-setenv =
-    PYTHONPATH = {toxinidir}
-
-[testenv:pep8]
-commands = flake8 --ignore=E501 --show-source src tests
-
-[testenv:py2]
-basepython = python2
-
-[testenv:py3]
-basepython = python3