Add black and flake8 tox commands

.travis.yml

@@ -52,7 +52,7 @@ matrix:
       env: DJANGO=master
 
     - python: 3.7
-      env: TOXENV=lint
+      env: TOXENV=black,flake8
 
   allow_failures:
     - env: DJANGO=master

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
         py{27,35,36,37}-django{111,20,21,22,master},
-        lint
+        black,flake8
 
 [travis:env]
 DJANGO =
@@ -26,8 +26,14 @@ deps =
     djangomaster: https://github.com/django/django/archive/master.zip
 commands = {posargs:py.test --cov=graphene_django graphene_django examples}
 
-[testenv:lint]
-basepython = python
-deps =
-    prospector
-commands = prospector graphene_django -0
+[testenv:black]
+basepython = python3.7
+deps = black
+commands  =
+    black graphene_django examples --check
+
+[testenv:flake8]
+basepython = python3.7
+deps = flake8
+commands =
+    flake8 graphene_django examples