My first NSRegularExpression matching!

Check user input using a regular expression.

There are still some things that should be fixed:
        - User shouldn’t be allowed to submit spaces or meaningless
text such as random symbols
        - Users’ input should be trimmed to use the first name only
even in the case that a first and last name or more names are provided
        - Input field should also greet the user if the user taps the
‘Return’ key within it

I’ve had a great time learning about NSRegularExpression and I hope
I’ll learn more about iOS and Mac development so I’ll be able to
immediately implement my ideas someday.