Reverted to id based relation setter

ref #13

src/errors/RunnerErrors.ts

@@ -1,5 +1,5 @@
-import { JsonController, Param, Body, Get, Post, Put, Delete, NotFoundError, OnUndefined, NotAcceptableError } from 'routing-controllers';
-import { IsInt, IsNotEmpty, IsPositive, IsString } from 'class-validator';
+import { IsString } from 'class-validator';
+import { NotAcceptableError, NotFoundError } from 'routing-controllers';
 
 /**
  * Error to throw when a runner couldn't be found.