Applying mime wrapper fix to avoid Angular CLI project build breaks

packages/core/src/sagas/sendFilesToPostActivitySaga.js

@@ -3,8 +3,7 @@ import {
   takeEvery
 } from 'redux-saga/effects';
 
-import mime from 'mime';
-
+import mime from '../utils/mime-wrapper';
 import whileConnected from './effects/whileConnected';
 
 import { SEND_FILES } from '../actions/sendFiles';

packages/core/src/utils/mime-wrapper.js

@@ -0,0 +1,15 @@
+/**
+ * @description
+ * This file wraps the mime library constructor to include '.json' types. This is needed
+ * to support Angular CLI web projects, in which the webpack.config files are hidden away
+ * from the user, and do not support .json file extension module resolutions.
+ * 
+ * Refer to issue https://github.com/jshttp/mime-types/issues/50#issuecomment-390932678
+ * and issue https://github.com/broofa/node-mime/issues/208.
+ * 
+ * This file may need to change if the mime library is bumped a major that may cause a
+ * breaking change, as it relies on the internal library file placement.
+ */
+
+import Mime from 'mime/Mime';
+export default new Mime(require('mime/types/standard.json'), require('mime/types/other.json'));