Increment a version number whenever the Smilie Extractor updates the bundled smilie store.

The version number is stored as NSPersistentStore metadata.
Add Smilies.framework tests to Awful app targets.
Periodically check for and download new smilies.

The new operations are:
* SmilieCleanUpDuplicateDataOperation, which runs immediately after bringing up a smilie data store, before doing anything else. The rest of the framework assumes there are no duplicate smilies.
* SmilieScrapeAndInsertNewSmiliesOperation, intended to be run periodically to look for and download any new smilies.
* SmilieDownloadMissingImageDataOperation, intended to be run on every launch. Probably makes sense to run after a scrape-and-insert operation.

In order to manage those operations, and to simplify framework use, a new SmilieKeyboard class is here. It wraps up a data store, a keyboard view, and an operation queue to manage the new operations.

In addition, the SmilieFetchedDataSource will no longer return smilies that have no image data.

Bonus:
* New TestDataStore class that uses an in-memory read-write store.
* Tidy up smilie tests imports, fixtures into Helpers.h.