default to USD in geo ip lookup.

Decided to put default logic in the GeoIpLookup.getCurrencyCode as
we are going to want this default everywhere we use it.

services/web/app/coffee/infrastructure/GeoIpLookup.coffee

@@ -30,5 +30,7 @@ module.exports = GeoIpLookup =
 
 	getCurrencyCode : (ip, callback)->
 		GeoIpLookup.getDetails ip, (err, ipDetails)->
+			if err? or !ipDetails?
+				return callback(null, "USD")
 			currencyCode = currencyMappings[ipDetails?.country_code?.toUpperCase()]
 			callback(err, currencyCode)

services/web/test/UnitTests/coffee/infrastructure/GeoIpLookupTests.coffee

@@ -82,3 +82,15 @@ describe "GeoIpLookup", ->
 			@GeoIpLookup.getCurrencyCode @ipAddress, (err, currencyCode)->
 				currencyCode.should.equal "EUR"
 				done()
+
+		it "should default to USD if there is an error", (done)->
+			@GeoIpLookup.getDetails = sinon.stub().callsArgWith(1, "problem")
+			@GeoIpLookup.getCurrencyCode @ipAddress, (err, currencyCode)->
+				currencyCode.should.equal "USD"
+				done()
+
+		it "should default to USD if there are no details", (done)->
+			@GeoIpLookup.getDetails = sinon.stub().callsArgWith(1)
+			@GeoIpLookup.getCurrencyCode @ipAddress, (err, currencyCode)->
+				currencyCode.should.equal "USD"
+				done()