Hemangshah Printer Versions Save

Code Refactoring and Improvements.

• Fixed a bug
• Updated for Swift 4.x (Dropped support for Swift 3.x)
• Added contributions file
• Updated Example for Swift 4.x

https://github.com/hemangshah/printer/issues/1

This release has been tested for Swift 4.0 and has a few new features since the last release. Stay tuned!