Add the ability to persist data outside of config items

[keegan-lillo]

Would be super handy to expose an API like clayConfig.storage.set('key', 'value') and clayConfig.storage.get('key') to allow developers to keep track of the state of the config without actually using the config to store things.

Config items can be set to persist as well if they have an ID set

{
  type: 'input',
  id: 'key'
  persist: true
}