router.post("/signup", (req, res, next) =>{
  bcrypt.hash(req.body.password, 10)
  .then(hash =>{
    const user = new User({
      email: req.body.email,
      password: hash
    });
    user.save()
      .then(result =>{
        res.status(201).json({
          message: 'User created!',
          result: result
        })
      })
      .catch(err => {
        res.status(500).json({
          error: err
        });
      });
  });
});