Add new takeScreenshots.js file

[KasimAhmic]

Builds on the original take_screenshots.js and adds a few QOL improvements:

• Uses yargs to parse the aruments and display help screen
• Gives the user the ability to run the screenshots in parallel
• Adds a log statement for when a directory doesn't exist and needs to be created
• Adds cleaner logging for which screenshot is being taken
• Adds a log statement telling the user how many screenshots are going to be taken
• Simplifies execution by passing all arguments as arrays and using a forEach loop on all of them resulting in a single reusable method
• Adds simple error handling to avoid UnhandledPromiseRejectionErrors and to auto close the program in the event of an exception
• Adds a console warning to the code sample page that tells the user the font the've typed in might not be valid. This warning is piped into takeScreenshots.js during the Puppeteer run and displayed in the terminal

[chriscoyier]

QOL indeed! Well done!