Improving installation instructions on mac.

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## Description
Improving installation, __particularly__ on mac.

## Expected Behavior
There were just a few hickups I ran into setting up current development environment. I would like to improve upon in readme.md.

## Specifications(For bug reports)

- Node version: 11.2
- Python version: 3.6.4
- npm version: 6.4.1
- Other dependencies:
- Operating system: Mac
- Command line used: terminal

P.S. : I also think the current setup is needs to be cut down. I currently run 4 terminal windows for only running development server which is pretty hacky.