Add precommit and isort

.isort.cfg

@@ -0,0 +1,2 @@
+[settings]
+known_third_party = aniso8601,graphql,graphql_relay,promise,pytest,pytz,pyutils,setuptools,six,snapshottest,sphinx_graphene_theme

.pre-commit-config.yaml

@@ -0,0 +1,24 @@
+repos:
+  - repo: git://github.com/pre-commit/pre-commit-hooks
+    rev: v1.3.0
+    hooks:
+      - id: check-json
+      - id: check-yaml
+      - id: debug-statements
+      - id: end-of-file-fixer
+        exclude: ^docs/.*$
+      - id: trailing-whitespace
+        exclude: README.md
+      - id: pretty-format-json
+        args:
+          - --autofix
+      - id: flake8
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v1.4.0
+    hooks:
+      - id: pyupgrade
+  - repo: https://github.com/ambv/black
+    rev: 18.6b4
+    hooks:
+      - id: black
+        language_version: python3