[Candidate] RE-add support to create candidates from the backend (unix user)

[ridz1208]

Brief summary of changes

The current code tries to get a username from the session. the session does not have a state when the candidate::createnew function is called from a script on the backend.

The new code is inpired by the database class which tries to use the environment username to create the data.

• Have you updated related documentation?

Testing instructions (if applicable)

1. make sure you can still create a candidate with no issue the standard way
2. try to create a candidate fro ma script in the backend

Link(s) to related issue(s)

• Resolves # (Reference the issue this fixes, if any.)

[GeorgeMurad]

LGTM