Analysis notification not displayed for the first analysis

When running an analysis for the first time, there is no pop-up indication on `AnalysisJob` and the UI freeze. The problem seems to come from the fact that `UserPreferenceService` methods calls to retrieve Checkers preferences is costing resources and taking time and not being run by a job appart.

To improve user experience, `AnalysisHandler` should call an *Checkers preferences retrieval* job and run the `AnalysisJob` only once this job is complete.