Add NullCacheAdapter accessor

Author: yuki-takeichi

spec/index.spec.js

@@ -248,6 +248,7 @@ describe('server', () => {
     expect(ParseServer.GCSAdapter).toThrow('GCSAdapter is not provided by parse-server anymore; please install parse-server-gcs-adapter');
     expect(ParseServer.FileSystemAdapter).toThrow();
     expect(ParseServer.InMemoryCacheAdapter).toThrow();
+    expect(ParseServer.NullCacheAdapter).toThrow();
     done();
   });
 

src/index.js

@@ -2,6 +2,7 @@ import ParseServer          from './ParseServer';
 import S3Adapter            from 'parse-server-s3-adapter'
 import FileSystemAdapter    from 'parse-server-fs-adapter'
 import InMemoryCacheAdapter from './Adapters/Cache/InMemoryCacheAdapter'
+import NullCacheAdapter     from './Adapters/Cache/NullCacheAdapter'
 import TestUtils            from './TestUtils';
 import { useExternal }      from './deprecated';
 import { getLogger }        from './logger';
@@ -21,4 +22,4 @@ Object.defineProperty(module.exports, 'logger', {
 });
 
 export default ParseServer;
-export { S3Adapter, GCSAdapter, FileSystemAdapter, InMemoryCacheAdapter, TestUtils, _ParseServer as ParseServer };
+export { S3Adapter, GCSAdapter, FileSystemAdapter, InMemoryCacheAdapter, NullCacheAdapter, TestUtils, _ParseServer as ParseServer };