Changed mcc API to always return a list, closes #4.

I changed one readme example from mcc 310 to 311, as 310 returns three
countries (Bermuda), which I found slightly less readable. Showing a two
country example already highlights the main point.
Merge pull request #7 from hannosch/multiple-countries-per-mcc

Changed mcc API to always return a list, closes #4.