replace imports of q with bluebird

update `package.json`

```
find src test -name '*.js' |
   xargs perl -i -pe 'if (/require\(.[qQ].\)/) { $_ = "import Promise from '\''bluebird'\'';\n"; }'

find src test -name '*.js' |
   xargs perl -i -pe 'if (/import [qQ]/) { $_ = "import Promise from '\''bluebird'\'';\n"; }'
```

src/utils/DecryptFile.js

@@ -20,7 +20,7 @@ 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 q from 'q';
+import Promise from 'bluebird';
 
 
 /**