LRU cache for dapps (#2006)

Conflicts:
	dapps/Cargo.toml
	dapps/src/lib.rs

dapps/src/lib.rs

@@ -60,6 +60,7 @@ extern crate rustc_serialize;
 extern crate parity_dapps;
 extern crate ethcore_rpc;
 extern crate ethcore_util as util;
+extern crate linked_hash_map;
 
 mod endpoint;
 mod apps;