Web UI: May include more functionality that is already provided by backend

[chrishkchris]

When I read the singa-auto/web/cURLutil.sh and singa_auto/admin/view
I found that there are some backend restful API that is not used by the web UI:

For example "Model delete"
backend restful API: https://github.com/nusdbsystem/singa-auto/blob/dev/singa_auto/admin/view/model.py#L133
curl example: https://github.com/nusdbsystem/singa-auto/blob/dev/web/cURLutil.sh#L97
The web UI doesn't have the delete function

We can include these functions in the web UI that are already provided by backend
In webUI we can use axios to call the backend API, e.g.
Upload dataset: https://github.com/nusdbsystem/singa-auto/blob/dev/web/src/containers/Datasets/UploadDataset.js#L134
Upload Model: https://github.com/nusdbsystem/singa-auto/blob/dev/web/src/containers/Models/UploadModel.js#L231
Inference: https://github.com/nusdbsystem/singa-easy/blob/master/web/src/ImageClassification/ImageClassification.js#L167

However, some backend API are not completed so we do not need to provide in Web UI,
e.g. Delete dataset: https://github.com/nusdbsystem/singa-auto/blob/dev/singa_auto/admin/view/datasets.py#L70