Homework 4.22.14 - MBTA stations in Ruby

Thanks for reviewing!

Changes I would like to make going forward:
  - Reduce repetitive code; this program would benefit from some methods!
  - Better validation for incorrect typed stations; the user has to type the station exactly as it is seen in the array (I do not downcase/manipulate it) --> in the meantime, I provided a list to the user of acceptable stations should an incorrect name be provided.

Initially stumbled on accessing array index values that are inside a hash; great hurdle to overcome.