GitLab

When creating a new Event with badly formatted images, a new event was
created without the images but the user was not notified of this. This
led to an event being created multiple times. With this commit the user
is redirected to an edit event view where he can change the images.

Upgrades the versions of webpack and related packages and replaces the
optimization in the build process with new methods (same as for
amiv-website instead of uglify-js). Also fixes some new linter errors that appeared because of new eslint-rules.

Instead of first submitting the images, the rest of the data is
submitted as JSON and afterwards the images with the new event
id (if a new event is created).

When cloning an event, unaccepted_count is now deleted, because this is
a read-only field.

Fixes some errors with the moderator field being undefined and the
submit button deleting fields from the form data (images).

Adds the option to set or edit a moderator for an event and displays it when viewing an event.

Displays the membership info in the list with participants of an event.

Addes a new menupoint to the admintool which enables users to see their
blacklist entries. Users who have blacklist readwrite permissions can
also create new entries and mark old ones as solved/payed.