Add category filtration to /search.

query/category_filter.js
	-Define a function that handles injecting category-filtration
	logic into elasticsearch queries.
	-Abstract it out into a standalone module since it's going to be
	used by both `query/search.js` and `query/reverse.js`.

sanitiser/search.js, test/unit/sanitiser/search.js
	-Add category filtration to `/search`.
	-Fixes (partly) #128

query/category_filter.js

@@ -0,0 +1,16 @@
+/**
+ * Inject the logic for filtering results by category into an elasticsearch
+ * query.
+ */
+
+'use strict';
+
+module.exports = function ( query, params ){
+  if( params.categories && params.categories.length > 0 ){
+    query.query.filtered.filter.bool.must.push({
+      terms: {
+        category: params.categories
+      }
+    });
+  }
+};

query/search.js

@@ -1,5 +1,6 @@
 
 var queries = require('geopipes-elasticsearch-backend').queries,
+    categoryFilter = require('./category_filter'),
     sort = require('../query/sort');
 
 function generate( params ){
@@ -44,7 +45,7 @@ function generate( params ){
   }
 
   query.sort = query.sort.concat( sort( params ) );
-
+  categoryFilter( query, params );
   return query;
 }
 

sanitiser/search.js

@@ -5,6 +5,7 @@ var _sanitize = require('../sanitiser/_sanitize'),
       size: require('../sanitiser/_size'),
       layers: require('../sanitiser/_layers'),
       details: require('../sanitiser/_details'),
+      categories: require('./_categories'),
       latlonzoom: require('../sanitiser/_geo')
     };
 

test/unit/sanitiser/search.js

@@ -8,6 +8,7 @@ var search  = require('../../../sanitiser/search'),
                       layers: [ 'geoname', 'osmnode', 'osmway', 'admin0', 'admin1', 'admin2', 'neighborhood', 
                                 'locality', 'local_admin', 'osmaddress', 'openaddresses' ], 
                       size: 10,
+                      categories: [],
                       details: true
                     },
     sanitize = function(query, cb) { _sanitize({'query':query}, cb); };