Support for field-level expiration settings

[thebadmonkeydev]

Not sure of the best API for this, but initially I was thinking something like this:

field :foo, Int, 'A complex calculated field', cache: { expires_in: 180.minutes }

There's also the possibility of using some custom DSL to allow for something like this:

field :foo, Int, 'A complex calculated field' do
  cache_expiry 180.minutes
end