US Military Address quotes from FedEx need calculators

[dpritchett]

USPS ships to military PO boxes (APO/FPO/DPO) per their site, and I've verified at least one sample military address gets a rate response. The only problem is they have different shipping method names and we don't have Spree calculators in place for them.

Sample API response: https://gist.github.com/dpritchett/a7335992dc318dafc24e

Edit to add: I did find a few non-military service class IDs that were returned:

 {
                 "CLASSID": "0",
                 "MailService": "First-Class Mail<sup>®</sup> Parcel",
                 "Rate": "2.86"
             }, {
                 "CLASSID": "4",
                 "MailService": "Standard Post<sup>®</sup>",
                 "Rate": "6.45"
             }, {
                 "CLASSID": "6",
                 "MailService": "Media Mail<sup>®</sup>",
                 "Rate": "2.69"
             }, {
                 "CLASSID": "7",
                 "MailService": "Library Mail",
                 "Rate": "2.56"
             ```

[dpritchett]

Relevant docs:

• https://www.usps.com/ship/apo-fpo-guidelines.htm (includes some sample destination addresses)
• https://about.usps.com/publications/pub640/pub640_tech.htm