Created page and form

Added the route and page for creating student folders.
Folder system unique entities

Moved code around so that you cannot have two filebases with the same
name in the same sub folder.
Better FileBase

All children of folders can now be accessed via the children class.
Also items with the same parent and same name aren't allowed. Order is
kept the same.
Fixed display and structure

Fixed the necessary controllers and templates to work with the new
entities. Also updated the structure so that collapsable nested folders
are possible.
Little security fix
Students can edit folders!
Fix foreign key bug

Fixed bug where children of students folders could not be deleted.
student folder bug fixes

Fixes bug with migration.
Fixes bug with having no-folders in the sidebar breaks everything.
Also makes username not show up in top right corner,.
Merge branch 'student-folders'