[Pki-devel] [PATCH] 29 Replaced daemon threads with executor service.

The certificate status update and retrieving modifications tasks have been modified to use the executor service. Unlike daemon threads, the service will allow existing task to exit gracefully before shutting down. An abandon operation is used terminate the persistent search used for retrieving modifications. Some methods have been moved to CertificateRepository class to simplify synchronizations. Ticket #73 This patch should be applied on top of #26 (or they can be squashed). There are some other threads that can be converted to use executor service as well, it will be done in separate patches. -- Endi S. Dewata