Add black dependency and Travis check

.travis.yml

@@ -16,6 +16,7 @@ python:
   - "3.6"
 
 stages:
+  - black
   - doc
   - test
 
@@ -45,6 +46,13 @@ install:
 
 jobs:
   include:
+    - stage: black
+      script:
+        - pip install black
+        - black --check theano/ setup.py
+    - &doctest
+      stage: doc
+      env: DOC=1 PART="theano/tests/test_flake8.py"
     - &normaltest
       stage: test
       env: FAST_COMPILE=1 FLOAT32=1 PART="theano --ignore=theano/tensor/nnet --ignore=theano/tensor/signal"

setup.py

@@ -98,7 +98,7 @@ def do_setup():
           install_requires=['numpy>=1.9.1', 'scipy>=0.14', 'six>=1.9.0'],
           # pygments is a dependency for Sphinx code highlight
           extras_require={
-              'test': ['nose>=1.3.0', 'flake8'],
+              'test': ['pytest', 'flake8', 'black'],
               'doc': ['Sphinx>=0.5.1', 'pygments']
           },
           package_data={