Support non-ASCII characters in user and project names

[SillyFreak]

We have many students in our JBC workshops with names that contain non-ASCII letters. We usually tell students to use their names to create users and projects, but Harrogate silently fails when such letters are present which leads to confusion.

It would thus be great to either 1) support such characters (the underlying file system shouldn't have a problem with non-ASCII file names) or at least 2) validate the input fields so that students know what they need to take care of when creating users/projects.

I hope that can be addressed in a future version of Harrogate :)