Add get user notification preference

[adafia]

What does this PR do?

This Pull Request adds an endpoint to give users the opportunity of getting their notification preferences

Description of Task to be completed?

This Pull Request adds an endpoint to give users the opportunity of getting their notification preferences

How should this be manually tested?

Database Setup (Postgres - Sequelize )

install dependencies and development dependencies

> npm install

create dataabase to postgresql

> createdb authorsHavenDb

remember to change the password in config.js file for development

create your config file

> create a .env file in your root directory and follow the `example.env`
file in setting up yours

add table to database

> sequelize db:migrate

The above command will migrate all table to your database

remove all tables from the database

> sequelize db:migrate:undo

The above command will revert any migration.

Any background context you want to provide?

Prior to this addition, users could only retrieve unseen notifications and couldn't get their notification preferences

What are the relevant pivotal tracker stories?

N/A

Screenshots (if appropriate)

N/A

Questions:

N/A