Mangles PO boxes

[topherhunt]

Hi there, thanks for all your work on this so far. I'm struggling to get Normalic to behave with PO boxes, but please let me know if there's a solution to this that I'm not seeing. I notice that PO boxes show up in some of the regexes in address.rb, so I assume that this is a bug rather than a missing feature.

When we try to parse a PO box address with Normalic, it drops the box number and decides that the street name is "Po". To reproduce:

address = Normalic::Address.parse("P.O. Box 1542, Concord, NH 03301")
# => Po, Concord, NH 03301
address.street
# => "Po"

We're using 0.2.