Merge pull request #125 from jagoPG/feature/multipart-xhr

After an upload failure return information from the backend for being…

src/plugins/Multipart.js

@@ -62,7 +62,7 @@ export default class Multipart extends Plugin {
           this.core.log(`Download ${file.name} from ${file.uploadURL}`)
           return resolve(file)
         } else {
-          this.core.emitter.emit('core:upload-error', file.id)
+          this.core.emitter.emit('core:upload-error', file.id, xhr)
           return reject('Upload error')
         }