Allow File Upload

[thortiede]

so far the file that holds the model tha should be persisted needs to be in the filesystem accessible by the appliation.

Add possibility to upload a file that is then persisted.

[thortiede]

Using MultipartFile uploads through the form-data files can be uploaded and their contents persisted. As of now the file is not stored on the server, only the contained model will be persisted.

To allow the storing of the file

• a filesystem needs to be accessible to the application where files can be stored,
• an index about those files needs to be created and possibly stored in an extra database and
• checks need to be put in that the file does not contain malicious content.

Since this seems overkill at the moment, this feature will stay as is at the moment and will be revisited again once the necessity to store the files arises.