improved express handler. createExpressHandler

[kennylavender]

See #37 for conversation.

Signature

createExpressHandler(disabledHandler: Function) => (enbaledHandler: Function) => ({ requiredFeature: String, features: [ ...Feature ]}) => void

The user can then use the more specific app.get, app.post etc. and they can still use app.use when their handlers do the method switching themselfs.

import { createExpressHandler } from '@parralleldrive/feature-toggles'

const notFoundHandler = (res, req, next) => {}

const todosHandler = (res, req, next) => {}

const features = []

app.get(
  '/todos',
  createExpressHandler(
    notFoundHandler,
    todosHandler,
    { requiredFeature: 'todos', features }
  )
)

function should be curried or auto-curried.