* Change addUserIdsForStatusAndProfileFetchingPoll to only ever receive arrays of user IDs
* Remove bufferCounter in favour of measuring array length
* Split addUserIdsForStatusAndProfileFetchingPoll into two separate actions
* Slightly simplify getPendingStatusesById
* Add DataLoaderInterval and use in actions/status_profile_polling
* Add tests for IntervalDataLoader
* Start adding DelayedDataLoader
* Updated DelayedDataLoader to split requested data into batches and made addIdsToLoad not return a promise by default
* Modify getMissingProfilesForIds to use a DataLoader and attach DataLoaders to the store
* Add tests for getMissingProfilesByIds loading statuses
* Revert change that defined getMissingProfilesByIds in a closure
* Change getMissingProfilesByUsernames to also use a DelayedDataLoader and add tests
* Pass extra argument into mocked version of Thunk
* Rename DataLoader.addIdsToLoad to DataLoader.queueForLoading
* Rename things and address feedback