Current user logic

[MrrrrFox]

Problem description

Currently the app does not provide any mechanism of user handling. Although FTTB we do not have the fronted & backend synced, we can prepare imitation of the logic as an initial setup for the mechanisms.

TO-DOs

• Add & handle onSubmit method to the login form #13
• Show current user data in the header
• Add possibiity for current user to logout (redirect to homepage & remove user data from cookie / local storage)
• Authenticate the user (redirect to homepage on ExperimentList & Experiment view when user is not logged in)