Local scheduler filters out dead clients during reconstruction (#1182)

* Object table lookup returns vector of DBClientID instead of address strings

* Add node IP address to DBClient notification

* DB client cache stores entire DB client, convert addresses to std::string

* get cached db client returns the client

* Expose a call to initialize the redis cache

* Local scheduler filters out dead clients during reconstruction

* Remove node ip address from dbclient, use aux_address for plasma managers

* Get entire db client entry when not found in cache

* Fix common tests

* Fix address in tests

* Push error to driver if driver task did the put

* Address Robert's comments and cleanup

* Remove unused Redis command

* Fix db test

src/common/format/common.fbs

@@ -111,7 +111,7 @@ table SubscribeToDBClientTableReply {
   client_type: string;
   // If the client is a local scheduler, this is the address of the plasma
   // manager that the local scheduler is connected to. Otherwise, it is empty.
-  aux_address: string;
+  manager_address: string;
   // True if the message is about the addition of a client and false if it is
   // about the deletion of a client.
   is_insertion: bool;