#166168820 Improve testing and coverage reports

[chidimo]

What does this PR do?

Improve testing and coverage

Description of Task to be completed?

1. Improve code coverage
2. Configure codeclimate test report and badge
3. Optimize pools by using one for all queries

How should this be manually tested?

1. Clone the repo
2. cd into the root folder on a cmd shell and run yarn install. PowerShell is fine also.
3. Setup a PostgreSQL DB.
4. Define a .env file in the root of the project and supply values for the following parameters

   JWT_SECRET=<json-web-token-secret>
   DBNAME=<database-name>
   PGPASSWORD=<postgres-db-password>
   PGHOST=<postgres-db-host>
   PGUSER=<postgres-db-user>
   PGPORT=<postgres-db-port>

5. Create a PostgreSQL database called testdb.
6. Run command yarn test

Any background context you want to provide?

What are the relevant pivotal tracker stories?

166168820

Screenshots (if appropriate)

Nil

Questions:

Nil