Some cleanup. Still not probing for roles/groups, but now has better docs and less code.
More cleanup. Group probing is now implemented.

For some reason, the user cookie isn't getting set on redirect. This may be solvable,
but it looks like a better approach will be to do this integration as a special
"standard servlet errai security impl" module which can be used instead of
errai-security-picketlink. I will make those changes on Monday.