Change from manual URL construction to using a lib

Makes the code cleaner to read and more resilient to changes

Fixes https://jira.coreos.com/browse/QUAY-940

static/js/services/util-service.js

@@ -1,3 +1,23 @@
+var urlParseURL = require('url-parse');
+
+var UrlBuilder = function(initial_url) {  
+  this.url = urlParseURL(initial_url || '', '/');
+};
+
+UrlBuilder.prototype.setQueryParameter = function(paramName, paramValue) {
+  if (paramValue == null) {
+    return;
+  }
+
+  this.url.query = this.url.query || {};
+  this.url.query[paramName] = paramValue;
+};
+
+UrlBuilder.prototype.toString = function() {
+  return this.url.toString();
+};
+
+
 /**
  * Service which exposes various utility methods.
  */
@@ -98,19 +118,23 @@ angular.module('quay').factory('UtilService', ['$sanitize', 'markdownConverter',
     };
 
     utilService.getRestUrl = function(args) {
-      var url = '';
+      var path = '';
+
       for (var i = 0; i < arguments.length; ++i) {
         if (i > 0) {
-           url += '/';
+          path += '/';
         }
-        url += encodeURI(arguments[i])
+        path += encodeURI(arguments[i])
       }
-      return url;
+    
+      return new UrlBuilder(path);
     };
 
     utilService.textToSafeHtml = function(text) {
       return $sanitize(utilService.escapeHtmlString(text));
     };
 
+    utilService.UrlBuilder = UrlBuilder;
+
     return utilService;
 }]);