Improve installation documentation in README.md

[Caffetaria]

Fix #200 README.md has been been made more understandable and I have fixed areas of potential confusion.

Description

In order to improve the documentation I have made the following changes-

1. Added a “Requirements Before Installation” section so that the users will not run into unexpected errors over the course of the installation process.
2. Changed port 80 to 8000 in Step 2 of 'Setting the environment variables' in order to make the document more consistent with step 4 under 'Start the server' which tells the user to go to localhost:8000.
3. Provided detailed steps for the section 'Setting up the database' to make it easier for contributors new to the project.
4. I have listed 'Production setup instructions' after the 'Development setup instructions' because all users will first need to understand the development setup instructions before they move on to the production setup. The rearranged order helps avoid confusion among new contributors.

Reviewers

@RishabhJain2018

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] Other

[wongalvis14]

I was about to add instructions to set up the config and postgresql, it's great to see someone else has the same idea!

However, I'm just wondering for users who just want to install it on their own server quick and simple, do they have to read through the development setup as well? I think I usually see production setup going before the development setup in other projects.