registerUser = (req = {}) => {
  return new Promise((resolve, reject) => {
    const user = new User({
      name: req.name,
      email: req.email,
      password: req.password,
      verification: uuid.v4()
    })
    user.save((err, item) => {
      if (err) {
        reject(buildErrObject(422, err.message))
      }
      resolve(item)
    })
  })
}
Registers a new user in database
@param {Object} req - request object