Rip out the remainder of Bluebird

src/utils/DecryptFile.js

@@ -21,7 +21,6 @@ import encrypt from 'browser-encrypt-attachment';
 import 'isomorphic-fetch';
 // Grab the client so that we can turn mxc:// URLs into https:// URLS.
 import MatrixClientPeg from '../MatrixClientPeg';
-import Promise from 'bluebird';
 
 // WARNING: We have to be very careful about what mime-types we allow into blobs,
 // as for performance reasons these are now rendered via URL.createObjectURL()