Changed the keys used for session

(logged_in only: None if no one is logged in, otherwise the email of the logged in account)
Lowercasing emails (from login form) + length verification
Changed logging to show more info
Merge branch 'dev' of github.com:INSA-4IF-SpecIFic/elif into dev
Fixed test that didn't pass (because of changes in Submission)
Merge branch 'dev' of github.com:INSA-4IF-SpecIFic/elif into dev

Conflicts:
	src/test_greedy.py