Change scripts for Google Map to Asynchronously

backend/app/views/comable/admin/orders/_google_map.slim

@@ -1,18 +1,29 @@
+javascript:
+  comable_google_map_element_id = "#{id}";
+  comable_google_map_address = "#{address.full_address}";
+
 coffee:
-  window.initialize_google_map = (element_id, address) ->
-    google_map = new google.maps.Map(document.getElementById(element_id), { zoom: 15 })
+  window.initialize_google_map_api = ->
+    return if google?
+    script = document.createElement('script')
+    script.type = 'text/javascript'
+    script.src = '//maps.googleapis.com/maps/api/js?v=3.exp&sensor=false&callback=initialize_google_map'
+    script.async = true
+    document.body.appendChild(script)
+
+  window.initialize_google_map = ->
+    google_map = new google.maps.Map(document.getElementById(comable_google_map_element_id), { zoom: 15 })
     google_geo = new google.maps.Geocoder()
-    google_geo.geocode({ address: address }, (result, status) =>
+    google_geo.geocode({ address: comable_google_map_address }, (result, status) =>
       return if status != google.maps.GeocoderStatus.OK
       location = result[0].geometry.location
       google_map.setCenter(location)
       new google.maps.Marker({ map: google_map, position: location })
     )
 
-javascript:
-  $(document).ready(function() {
-    initialize_google_map('#{id}', '#{address.full_address}');
-  })
+  $(document).ready(->
+    initialize_google_map_api()
+  )
 
 .comable-map
   .comable-google-map id="#{id}"

backend/app/views/layouts/comable/admin/application.slim

@@ -18,9 +18,6 @@ html
     = stylesheet_link_tag 'http://rawgithub.com/aehlke/tag-it/master/css/tagit.ui-zendesk.css', media: 'all', 'data-turbolinks-track' => true
     = javascript_include_tag 'http://rawgithub.com/aehlke/tag-it/master/js/tag-it.min.js', 'data-turbolinks-track' => true
 
-    / TODO: Refactoring
-    = javascript_include_tag '//maps.google.com/maps/api/js?v=3&sensor=false', 'data-turbolinks-track' => true
-
     = csrf_meta_tags
 
   body id="#{"comable-#{controller_name.singularize}"}"