I wanted to know the category/categories of my reverse lookups on a l…

…on/lat. I realized it was already plumbed everywhere, except for the sanitizer entry in the middleware.

This patch adds the support for categories by passing a get parameter just like https://github.com/pelias/documentation/blob/master/place.md

sanitizer/reverse.js

@@ -37,7 +37,8 @@ module.exports.middleware = (_api_pelias_config) => {
     geo_reverse: require('../sanitizer/_geo_reverse')(),
     boundary_country: require('../sanitizer/_boundary_country')(),
     request_language: require('../sanitizer/_request_language')(),
-    boundary_gid: require('../sanitizer/_boundary_gid')()
+    boundary_gid: require('../sanitizer/_boundary_gid')(),
+    categories: require('../sanitizer/_categories')()
   };
 
   // middleware