Stratify notifications for callback failure

The OS will let you know whenever it reaches one of the follwing two
conditions:
    - A user setting changed the input type.
    - The callback was delayed for too long.

We will notify the user whatever was the case that made the keylogger
fail, this will hopefully make things easier to debug on the long run.
Add use of grand central dispatch for db querying

Querying to the database from within the data manager is now done in a
background thead, which makes GUI responsive during the querying
process.
Add waiting for confirmation flag