Extra checks to hopefully fix #68
Fixing Travis build (I hope)

XCTest is apparently not supported on iOS 6.
Fix crash if +closeDatabase is called before database is ever opened (fix #79)
Use REAL for date
Merge pull request #80 from l4u/patch-1

Use REAL for date in README example
Removing Travis after too many false alarms. This is supposed to save needless work, not create more of it.
postChangeNotification: Send instance, not class
Exception 'FCModel tables must have a single-column primary key' should appear for multi-key tables.
Merge pull request #82 from lickel/notification-update-notif

postChangeNotification: Send instance, not class
Merge pull request #83 from ilyannn/master

Enforce 'FCModel tables must have a single-column primary key'
Fix #85
Remove redundant brackets around NSNumber literals.
Merge pull request #88 from DaleJefferson/master

Remove redundant brackets around NSNumber literals.
Removing warnings in the test project.
Replace FCModelDatabaseQueueOperation with NSBlockOperation

NSBlockOperation offers the same functionality as
FCModelDatabaseQueueOperation. Less code is happier code!
Add database queue method to run blocks asynchronously

I find myself using a pattern like this to prevent the database
blocking my main thread:

```obj-c
FCModelDatabaseQueue *databaseQueue = …
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT
, 0), ^{
    [databaseQueue inDatabase:^(FMDatabase *database) {
        // queries & updates

      [[NSOperationQueue mainQueue] addOperationWithBlock:^{
          // update the UI
      }];
    }];
});
```

This is a little wasteful though, the global queue's worker thread is
now blocked waiting for the database queue's worker thread to return
control.

With an async method to `FCModelDatabaseQueue` the same example looks
like this:

```obj-c
    FCModelDatabaseQueue *databaseQueue = …
    [databaseQueue inDatabaseAsync:^(FMDatabase *database) {
        // queries & updates

        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            // update the UI
        }];
    }];
```
Merge pull request #90 from randomsequence/master

Replace FCModelDatabaseQueueOperation with NSBlockOperation, add async block call
New internal notification to ensure FCModelCachedObjects expire before your app responds to FCModel change notifications
fix [FCModel databaseIsOpen]
Merge pull request #92 from ilyannn/fix-isOpen

fix [FCModel databaseIsOpen]