feat(service): add file map lookup into static-files loader

This adds support for file cache revisioning.

Usage example: test/unit/service/loader-static-files.spec.js

PR #1593

src/service/loader-static-files.js

@@ -10,7 +10,7 @@ angular.module('pascalprecht.translate')
  * "lang-en_US.json", "lang-de_DE.json", etc. Using this builder,
  * the response of these urls must be an object of key-value pairs.
  *
- * @param {object} options Options object, which gets prefix, suffix and key.
+ * @param {object} options Options object, which gets prefix, suffix, key, and fileMap
  */
 .factory('$translateStaticFilesLoader', $translateStaticFilesLoader);
 
@@ -36,12 +36,18 @@ function $translateStaticFilesLoader($q, $http) {
         throw new Error('Couldn\'t load static file, no prefix or suffix specified!');
       }
 
+      var fileUrl = [
+        file.prefix,
+        options.key,
+        file.suffix
+      ].join('');
+
+      if (angular.isObject(options.fileMap) && options.fileMap[fileUrl]) {
+        fileUrl = options.fileMap[fileUrl];
+      }
+
       return $http(angular.extend({
-        url: [
-          file.prefix,
-          options.key,
-          file.suffix
-        ].join(''),
+        url: fileUrl,
         method: 'GET',
         params: ''
       }, options.$http))

test/unit/service/loader-static-files.spec.js

@@ -21,6 +21,7 @@ describe('pascalprecht.translate', function () {
       $translationCache = _$translationCache_;
 
       $httpBackend.when('GET', 'lang_de_DE.json').respond({HEADER: 'Ueberschrift'});
+      $httpBackend.when('GET', 'lang_de_DE.123.json').respond({HEADER: 'Ueberschrift'});
       $httpBackend.when('GET', 'lang_en_US.json').respond({HEADER:'Header'});
       $httpBackend.when('GET', 'lang_nt_VD.json').respond(404);
     }));
@@ -62,6 +63,19 @@ describe('pascalprecht.translate', function () {
       $httpBackend.flush();
     });
 
+    it('should fetch static files from file map when invoking', function () {
+      $httpBackend.expectGET('lang_de_DE.123.json');
+      $translateStaticFilesLoader({
+        key: 'de_DE',
+        prefix: 'lang_',
+        suffix: '.json',
+        fileMap : {
+          'lang_de_DE.json' : 'lang_de_DE.123.json'
+        }
+      });
+      $httpBackend.flush();
+    });
+
     it('should return a promise', function () {
       var promise = $translateStaticFilesLoader({
         key: 'de_DE',