Makefile: added -DNDEBUG to compilation flags

Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
LRU: use boost intrusive list instead of std::list

Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
LRU: update the items LRU positions not more than once per 60 seconds

Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>