cache manager and clearing tracing cache (#1769)

* removed configure_cache method

* generic cache_manager struct

* fixed #1743, tracing caches are cleared

* removed deadlocks in garbage_collect, implemented HeapSizeOf for traces

* trace cache config

* fixed carbage typo

ethcore/src/lib.rs

@@ -118,6 +118,7 @@ pub mod snapshot;
 pub mod action_params;
 #[macro_use] pub mod evm;
 
+mod cache_manager;
 mod blooms;
 mod db;
 mod common;