storage-node: removed unsed imports

storage-node/packages/colossus/lib/app.js

@@ -33,7 +33,6 @@ const yaml = require('js-yaml');
 const validateResponses = require('./middleware/validate_responses');
 const fileUploads = require('./middleware/file_uploads');
 const pagination = require('@joystream/storage-utils/pagination');
-const storage = require('@joystream/storage-node-backend');
 
 // Configure app
 function create_app(project_root, storage, runtime)

storage-node/packages/colossus/paths/asset/v0/{id}.js

@@ -20,9 +20,6 @@
 
 const path = require('path');
 
-const file_type = require('file-type');
-const mime_types = require('mime-types');
-
 const debug = require('debug')('joystream:colossus:api:asset');
 
 const util_ranges = require('@joystream/storage-utils/ranges');