Add flake8 pre-commit hook

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: 3.8.3
+    hooks:
+      - id: flake8

Makefile

@@ -0,0 +1,3 @@
+setup-flake8-hook:
+	python3 -m venv env
+	. env/bin/activate && pip install pre-commit && pre-commit install && git config --bool flake8.strict true

README.md

@@ -40,6 +40,10 @@ This file contains all the required environment variable for the application. Sa
 
 The actual values are added to `ready-to-trade` vault. Please use the values corresponding to the `dev` environment.
 
+## Set up a flake8 pre-commit hook locally
+To set up a pre-commit hook which will prevent you from committing code with formatting errors, run:
+`make setup-flake8-hook`
+
 ### Single Sign On (SSO)
 
 The app works out of the box with