Add PermissionModule and GroupsModule

Both currently contain only the database entities, taken from the schema.

Signed-off-by: David Mehren <git@herrmehren.de>

src/permissions/note-user-permission.entity.ts

@@ -0,0 +1,14 @@
+import { Column, ManyToOne } from 'typeorm/index';
+import { Note } from '../notes/note.entity';
+import { User } from '../users/user.entity';
+
+export class NoteUserPermission {
+  @ManyToOne(_ => User)
+  user: User;
+
+  @ManyToOne(_ => Note)
+  note: Note;
+
+  @Column()
+  canEdit: boolean;
+}