Evaluate removing Spring Security

[tulioag]

Currently using Spring Security doesn't seem to be providing great value. There is much boilerplate needed for making it work and removing it will probably make the code base smaller. Dynamic routes can be added after login depending on the user's role as an alternative security solution.

The current boilerplate could be moved to a separate addon. In that case it could make sense to use it still.

Relates to #736

[web-padawan]

Covered by 9a19c9a.