Limit robots displayed in entity search

Before, we'd load *all* the robots, which can be a huge issue in namespaces with a large number of robots. Now, we only load the top-20 robots (as per recency in login), and we also limit the information returned to the entity search to save some bandwidth.

Fixes https://jira.coreos.com/browse/QUAY-927

static/js/services/api-service.js

@@ -71,7 +71,7 @@ angular.module('quay').factory('ApiService', ['Restangular', '$q', 'UtilService'
       if (used[paramName]) { continue; }
 
       var value = parameters[paramName];
-      if (value) {
+      if (value != null) {
         url += isFirst ? '?' : '&';
         url += paramName + '=' + encodeURIComponent(value)
         isFirst = false;