Merge branch 'develop' of https://code.ornl.gov/eagle-i/common_package into develop

## Scripts

Contains a script for testing the connection to a database `test-db-conn`

Set variables in the script to match:

- DB_HOST: a string representing the hostname or IP address hosting the database (default localhost)

- DB_PORT: an integer representing the port to connect to the database on (default 5432)

- DB_DB: a string representing the database to connect to (default postgres)

- MAX_RETRIES: an integer representing the maximum number of times to retry the connection (default 60)

Usage: `test-db-conn -d <DB_DB> -h <DB_HOST> -p <DB_PORT> -r <MAX_RETRIES>`

## Classes

Database(ABC) is and abstract class that can be found in `database.py`.

Database takes in environmental variables for connection to a database: 

DATABASE_TIMEOUT, DATABASE_DB, DATABASE_USER, DATABASE_PW, DATABASE_HOST,

DATABASE_PORT, DATABASE_SCHEMA

These environmental variables are read in using `env.py` function check_environment and have default values assigned.

Best practice is to use `with` to enter the database, i.e. `with Database as db:`

## Mixins

## Functions