Fix specs using Travis CI with VCR cassettes

@imajes - I just wanted to let you know that I got this to work with the postalmethods.com API.  It also now runs on Travis CI using VCR cassettes.  I did have to mark a few specs as pending, and I made a number of other changes, yet there is still a lot of work to do.

At any rate, even if you don't care to merge this in, it might be useful for others if you point to my repo.

Thank you so much for your original work!
Chip