added /user DELETE route

src/routes/validate/user.ts

@@ -25,6 +25,8 @@ export default class UserValidate {  // validate input for user
       .allow('')
   };
 
+  private static specialUsernames = ['admin', 'user', 'key', 'new', 'passreset'];  // names a user cannot take
+
   static input (data, param) {
     if (param === 'new') {
       return joi.object({
@@ -71,4 +73,8 @@ export default class UserValidate {  // validate input for user
     }).validate(data, {stripUnknown: true})
     return error !== undefined? null : value;
   }
+
+  static isSpecialName (name) {  // true if name belongs to special names
+    return this.specialUsernames.indexOf(name) > -1;
+  }
 }