Implement asynchroneous requests

[Gui-FernandesBR]

Benefits:

• Speed up code when requesting several distances from APIs
• Learn a new good and useful stuff!

[Gui-FernandesBR]

A few months ago I had the chance to implement batch async requests when retrieving multiple distances from OSM and GMaps. It all worked well, however the files I've used are no longer available since Dec 26th.