Library editor forces a dump of an optional key "uses:{}" for the available libraries when the field is empty
#### Summary
The library editor requires fixing. The key "uses" is set mandatory during the dump when it should actually be an optional field
#### Steps to reproduce
The bug is identified here:
https://gitlab.idiap.ch/beat/beat.editor/blob/v2/beat/editor/test/test_libraryeditor.py#L40
and explained in detail: https://gitlab.idiap.ch/beat/beat.core/merge_requests/79
#### What is the current bug behavior?
The current behavior forces the library to have a dump "uses" key
#### What is the expected correct behavior?
The schema of the library is explicit about it being an optional field. So if empty we should not get a "uses:{}" at the dump
The test needs to be fixed accordingly
#### Relevant code:
https://gitlab.idiap.ch/beat/beat.editor/blob/v2/beat/editor/test/test_libraryeditor.py#L40
issue