Add httmock
Replace mock with HTTMock
Add test get current
Split get_distance property

Split get_distance property into a method called _compute_distance
that calculates the distance and a variable name distance_km
that calls on _compute_distance.
Change get_distance_mi to distance_mi

Change get_distance_mi property to distance_mi a variable.
Add display_full_kilometer
Add display_full_miles
Fix misspelt word