Added .env support

[pandfun]

What does this PR do?

Add support to .env files.

Test Plan

1. Installed the dot-env npm package
2. Created a .env.example to show users how to use it.
3. Updated app.js to fetch the api key, project id, etc using the .env file.
4. Added .env to .gitignore.
5. Updated README.md to reflect the new installation steps.

Related PRs and Issues

Closes: #14

Have you read the Contributing Guidelines on issues?

Yes