Command line implementation of invoice commands (#96)

* add issue_invoice_tx command

* rustfmt

* add first pass at process_invoice command

* start of process_invoice fn

* rustfmt

* rename issue invoice and process invoice to invoice and pay

* add prompting and display information to pay invoice command

* rustfmt

* support invoice transactions in finalize command

* rustfmt

controller/tests/invoice.rs

@@ -124,6 +124,7 @@ fn invoice_tx_impl(test_dir: &str) -> Result<(), libwallet::Error> {
 				..Default::default()
 			};
 			slate = api.process_invoice_tx(&slate, args)?;
+			api.tx_lock_outputs(&slate)?;
 			Ok(())
 		})?;