Change tutor availability

Once the tutor availability has been setup during registration, it is not possible to update them.

added Bug label

assigned to @DavePikopPokam

mentioned in issue #160

added Registraton label

created branch 176-change-tutor-availability to address this issue

I suggested a few weeks ago creating a tutor profile that allows each tutor to update their information (bio, availability, etc.) @sbibauw @bridubois Do you have any clue how I should implement this?

We can probably have an "account" page in the user menu (the same that the one to deconnect) with ability to edit those values