Add missing __block on track: method

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
Remove unnecessary archiveQueue: that may cause a concurrency problem

Fixes a concurrency problem that may occurs when HTTP events queue is changed
by applicationDidBecomeActive: while applicationWillResignActive: is being accessed.

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
Change archiveQueue:forToken: from NSMutableArray to NSArray

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
Restore number of retires of failed request to 40

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>