Add confirm command to wallet, and update RPU to check bank for a signature

src/request.rs

@@ -1,7 +1,7 @@
 //! The `request` module defines the messages for the thin client.
 
 use hash::Hash;
-use signature::PublicKey;
+use signature::{PublicKey, Signature};
 
 #[cfg_attr(feature = "cargo-clippy", allow(large_enum_variant))]
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -9,6 +9,7 @@ pub enum Request {
     GetBalance { key: PublicKey },
     GetLastId,
     GetTransactionCount,
+    GetSignature { signature: Signature },
 }
 
 impl Request {
@@ -20,7 +21,17 @@ impl Request {
 
 #[derive(Serialize, Deserialize, Debug)]
 pub enum Response {
-    Balance { key: PublicKey, val: Option<i64> },
-    LastId { id: Hash },
-    TransactionCount { transaction_count: u64 },
+    Balance {
+        key: PublicKey,
+        val: Option<i64>,
+    },
+    LastId {
+        id: Hash,
+    },
+    TransactionCount {
+        transaction_count: u64,
+    },
+    SignatureStatus {
+        signature_status: Option<(Hash, Signature)>,
+    },
 }