Fixed dialog not showing in QueueUploader, login consistency

- removed individual API pref keys for saving login information and made library conformed to the keys defined in ISKeys.h.  As a result, logging in at the QueueUploaderView will now properly save credentials that will be picked up by the CredentialManager, as they should
- got the dispatch dialogs to actually show when logging in/uploading, and make API tasks work in the background thread

#7