Resolve "Edit Files section"

@mobreza please check. Now it works for upload and delete file. For updating repositoryFiles, on server has to be changed DatasetFilesController.addFileToDataset and RepositoryService to be able to update repositoryFiles. First time it receives

@RequestParam("file") final MultipartFile inputFile

On update it receives RepositoryFile as FormData, for example:

@RequestParam("uuid") final UUID repositoryFileUUID, @RequestParam("title") final String title, @RequestParam("description") final String description...

Off course there are can be few methods, such as upload/update, but for now it's not supported on server.

Closes #162 (closed)