fix error sharing image and failing to upload, fix upload in webkit/safari, and test it

src/components/PhotoDialog.vue

@@ -350,6 +350,7 @@ export default class PhotoDialog extends Vue {
     const token = await accessToken(this.activeDid);
     const headers = {
       Authorization: "Bearer " + token,
+      // axios fills in Content-Type of multipart/form-data
     };
     const formData = new FormData();
     if (!this.blob) {