D-Net

added cache layer issn lookups. Lasts 5 min (300 sec) and caches are invalidated each time a subscription is added or removed

using cache for subscription access, added cache manager

using cache for subscription access

Cleaned configuration for interceptor logging request to the persistent existDB

Using customised interceptor to log invocation time of xqueries

Added AOP Interceptors on existDatabase

moved tests resources from src/main to src/test