Implement #name method for MaxMind lookup.

Also add test for method presence in all lookups.

lib/geocoder/lookups/maxmind.rb

@@ -5,6 +5,10 @@ require 'csv'
 module Geocoder::Lookup
   class Maxmind < Base
 
+    def name
+      "MaxMind"
+    end
+
     private # ---------------------------------------------------------------
 
     def results(query)

test/lookup_test.rb

@@ -3,6 +3,14 @@ require 'test_helper'
 
 class LookupTest < Test::Unit::TestCase
 
+  def test_responds_to_name_method
+    Geocoder::Lookup.all_services.each do |l|
+      lookup = Geocoder::Lookup.get(l)
+      assert lookup.respond_to?(:name),
+        "Lookup #{l} does not respond to #name method."
+    end
+  end
+
   def test_search_returns_empty_array_when_no_results
     Geocoder::Lookup.all_services_except_test.each do |l|
       lookup = Geocoder::Lookup.get(l)