#161966910 Implement User Registration Feature

Implement user registration feature
Description of Task to be completed?
implement user registration endpoint
Use regex to ensure data passed by the user meets the criteria set.
How should this be manually tested?
1. git clone -b ft-user-registration-162541314 https://github.com/andela/ah-infinity-stones and $ cd ah-infinity-stones
2. Create and activate virtual env
virtualenv -p python3 venv
$ source venv/bin/activate
1. $ pip3 install -r requirements.txt to install the dependencies
2. Setup environment variables. Copy all from below and paste them into the .env file. Update the values to your choice.
```
export DATABASE_USER='user'
export DATABASE_PASSWORD='password'
export HOST='localhost'
export PORT='5432'
export DATABASE_TEST='ah_test'
```
  Activate the env variables by $source .env.
3. Run migrations: $ python3 manage.py migrate
4. Run app - $ python3 manage.py runserver
5. Acess http://127.0.0.1:8000/api/users/ through Postman, provide inputs in the following format and submit.
```
{ "user": {
"username": "username44",
"email": "username@user.com",
"password": "@Password321"  
}
}
```
6. Run testspython3 manage.py test authors.apps.authentication.tests.test_registration
  What are the relevant pivotal tracker stories?
  
  #161966910
  
  Screenshots

andela / ah-infinity-stones