Add Registrant API contact update action

Closes #849

app/models/contact/address.rb

@@ -0,0 +1,25 @@
+class Contact
+  class Address
+    attr_reader :street
+    attr_reader :zip
+    attr_reader :city
+    attr_reader :state
+    attr_reader :country_code
+
+    def initialize(street, zip, city, state, country_code)
+      @street = street
+      @zip = zip
+      @city = city
+      @state = state
+      @country_code = country_code
+    end
+
+    def ==(other)
+      (street == other.street) &&
+        (zip == other.zip) &&
+        (city == other.city) &&
+        (state == other.state) &&
+        (country_code == other.country_code)
+    end
+  end
+end