add cancel script

bin/lamassu-cancel

@@ -0,0 +1,25 @@
+#!/usr/bin/env node
+
+const uuid = require('@fczbkk/uuid4')
+
+const tx = require('../lib/cash-out-tx')
+
+const argv = process.argv.slice(2)
+
+if (argv.length !== 1) {
+  console.log('Usage: lamassu-cancel <tx-id>')
+  console.log('Cancels the cash out transaction with given tx-id so it cannot be dispensed.')
+  process.exit(1)
+}
+
+const txId = argv[0]
+
+if (!uuid.validate(txId)) {
+  console.log('tx-id must be valid uuid. e.g.: f8093ded-c542-4916-8ab5-6ebeceb287c1')
+  process.exit(2)
+}
+
+tx.cancel(txId)
+.then(() => console.log('Success.'))
+.catch(err => console.log(`Error: ${err.message}`))
+.then(() => process.exit(0))