Implement the http variant of the bank server.

During that process, many shortcomings with the socket server and the
bank lib were fixed.

I am aware a massive commit like this is not ideal.

socket-server/src/commands/get_account_nrs.rs

@@ -16,12 +16,10 @@ impl Command for GetAccountNrs {
         info!("getting account numbers...");
 
         let bank = bank.read().unwrap();
-        let nrs: Vec<String> = bank.account_numbers()
-            .into_iter()
-            .collect();
+        let nrs: Vec<String> = bank.account_numbers().into_iter().collect();
 
         let written = stream.write(&protocol::account_nrs(&nrs))?;
 
         Ok(written)
     }
-}
+}