Add target for python 3.8 & cleanup travis script

.travis.yml

@@ -1,42 +1,20 @@
-dist: xenial
+dist: bionic
 sudo: true
 language: python
-matrix:
-    include:
-      # Python version is just for the look on travis.
-        - python: 2.7
-          env: TOX_ENV=py27-django111
-
-        - python: 3.5
-          env: TOX_ENV=py35-django111
-        - python: 3.5
-          env: TOX_ENV=py35-django20
-        - python: 3.5
-          env: TOX_ENV=py35-django21
-        - python: 3.5
-          env: TOX_ENV=py35-django22
-
-        - python: 3.6
-          env: TOX_ENV=py36-django111
-        - python: 3.6
-          env: TOX_ENV=py36-django20
-        - python: 3.6
-          env: TOX_ENV=py36-django21
-        - python: 3.6
-          env: TOX_ENV=py36-django22
-
-        - python: 3.7
-          env: TOX_ENV=py37-django20
-        - python: 3.7
-          env: TOX_ENV=py37-django21
-        - python: 3.7
-          env: TOX_ENV=py37-django22
-        - python: 3.7
-          env: TOX_ENV=py37-djangostable
-
-        - env: TOX_ENV=lint
+python:
+  - 2.7
+  - 3.5
+  - 3.6
+  - 3.7
+  - 3.8
+stages:
+  - lint
+  - test
+jobs:
+  include:
+    - { stage: lint, env: TOXENV=flake8, python: 3.6 }
 
 script:
-    - tox -e $TOX_ENV
+    - tox
 install:
-    - pip install tox
+    - pip install tox tox-travis

tox.ini

@@ -2,9 +2,16 @@
 envlist =
     py{27,35,36}-django111
     py{35,36,37}-django{20,21,22}
-    py37-djangostable
+    py{37,38}-djangostable
     lint
 
+[tox:travis]
+2.7 = py27
+3.5 = py35
+3.6 = py36
+3.7 = py37
+3.8 = py38
+
 [testenv]
 setenv=PYTHONWARNINGS=d
 deps =
@@ -18,7 +25,7 @@ commands =
     python --version
     pip install -e .
     pip freeze
-    coverage run --branch --source=mail_factory demo/manage.py test mail_factory
+    coverage run --branch --source=mail_factory demo/manage.py test {posargs:mail_factory}
     coverage report -m --omit=mail_factory/test*
 
 [testenv:lint]