TT#19230 Bump django from 1.11.23 to 1.11.28 (security update)

> https://www.djangoproject.com/weblog/2020/feb/03/security-releases/

* add pre-commit config and update README.md about it
  This will help to tidy the code

Change-Id: I769f847e3ac0c64221aebbc5d850bb331371ced8

.pre-commit-config.yaml

@@ -0,0 +1,13 @@
+default_language_version:
+    # force all unspecified python hooks to run python3
+    python: python3
+repos:
+-   repo: https://github.com/psf/black
+    rev: stable
+    args: -t py37
+    hooks:
+    -   id: black
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    -   id: flake8

README.md

@@ -14,6 +14,16 @@ Run docker containers
 Prepare development environment
 ===============================
 
+On your desktop, install pre-commit tool
+
+[pre-commit](https://pre-commit.com/)
+-------------------------------------
+
+  * apt install build-essential python3-dev python3-virtualenvwrapper virtualenvwrapper
+  * mkvirtualenv repos-scritps --python=python3
+  * pip3 install pre-commit
+  * pre-commit install
+
 Inside the repoapi-stretch container run:
 
     $ export VAR_DIR=/tmp/repoapi

requirements/common.txt

@@ -1,4 +1,4 @@
-Django==1.11.23
+Django==1.11.28
 django-extensions
 yuicompressor
 django-assets