[accounts/ui/statistics/navigation] updated look and feel of accounts from feedbacks

beat/web/accounts/api.py

beat/web/accounts/static/accounts/js/dialogs.js

...ccounts/templates/accounts/dialogs/change_supervisor.html

...ounts/templates/accounts/dialogs/validate_supervisee.html

beat/web/accounts/templates/accounts/settings.html

beat/web/navigation/admin.py

beat/web/statistics/templates/statistics/statistics.html

beat/web/ui/registration/forms.py

.../web/ui/registration/templates/registration/activate.html

...plates/registration/mail.account_revalidation.message.txt

...emplates/registration/mail.godfather_rejected.message.txt

...mplates/registration/mail.godfather_rejection.message.txt

...mplates/registration/mail.godfather_validated.message.txt

...plates/registration/mail.godfather_validation.message.txt

...l.godfather_validation_supervisee_add_request.message.txt

...lates/registration/mail.migration_10_accounts.message.txt

...egistration/templates/registration/registration_form.html

beat/web/ui/views.py