"concurrency" field is not handled

[AlexisNeveu]

Describe the bug

When trying to draw a job containing the field named "concurrency", it does not draw the model.
To Reproduce

Steps to reproduce the behavior:

1. Go to the text view
2. Type a code with a job containing a concurrency field
3. Click on 'draw'
4. See that it is not correctly drawn

Expected behavior
The concurrency field should be accepted and the rest of the model should be drawn correctly.

Screenshots

Application (please complete the following information):

• leto-modelizer commit hash 280a6e5ffd4bcb75bc8e3c8d4e20c787ea067222
• githubator-plugin commit hash b02edb8

Desktop (please complete the following information):

• OS: Ubuntu
• Browser FireFox