Execution fixes plus black (#8)

* Fixed execution class execution
* Added support for black autoformatting
* Reformatted everything with black

.flake8

@@ -1,3 +1,4 @@
 [flake8]
+ignore = E203,W503,E704
 exclude = .git,.mypy_cache,.pytest_cache,.tox,.venv,__pycache__,build,dist,docs
 max-line-length = 88

.travis.yml

@@ -4,17 +4,18 @@ dist: xenial
 sudo: true
 
 python:
-  - 3.6
-  - 3.7
+    - 3.6
+    - 3.7
 
 install:
-  - pip install pipenv
-  - pipenv install --dev
+    - pip install pipenv black
+    - pipenv install --dev
 
 script:
-  - flake8 graphql tests
-  - mypy graphql
-  - pytest --cov-report term-missing --cov=graphql
+    - flake8 graphql tests
+    - black graphql tests --check
+    - mypy graphql
+    - pytest --cov-report term-missing --cov=graphql
 
 after_success:
-  - coveralls
+    - coveralls

Pipfile

@@ -5,6 +5,8 @@ name = "pypi"
 
 [dev-packages]
 graphql-core-next = {path = ".", editable = true}
+# Line below commented as causes issues with Pipenv
+# black = "18.6b4"
 flake8 = "*"
 mypy = "*"
 pytest = "*"