Storage stage updates

* Remove logging init from storage program: saw a crash in a test
  indicating the logger being init'ed twice.
* Add entry_height mining proof to indicate which segment the result is
  for
* Add an interface to get storage miner pubkeys for a given entry_height
* Add an interface to get the current storage mining entry_height
* Set the tvu socket to 0.0.0.0:0 in replicator to stop getting entries
  after the desired ledger segment is downloaded.
* Use signature of PoH height to determine which block to download for
  replicator.

src/rpc_request.rs

@@ -54,6 +54,8 @@ pub enum RpcRequest {
     SignVote,
     DeregisterNode,
     GetStorageMiningLastId,
+    GetStorageMiningEntryHeight,
+    GetStoragePubkeysForEntryHeight,
 }
 
 impl RpcRequest {
@@ -97,6 +99,8 @@ impl RpcRequest {
             RpcRequest::SignVote => "signVote",
             RpcRequest::DeregisterNode => "deregisterNode",
             RpcRequest::GetStorageMiningLastId => "getStorageMiningLastId",
+            RpcRequest::GetStorageMiningEntryHeight => "getStorageMiningEntryHeight",
+            RpcRequest::GetStoragePubkeysForEntryHeight => "getStoragePubkeysForEntryHeight",
         };
         let mut request = json!({
            "jsonrpc": jsonrpc,