Update README to document event parameters correctly

Author: John Barton

README.md

@@ -47,15 +47,15 @@ var backup = new DynamoBackup({
 });
 
 backup.on('error', function(data) {
-    console.log('Error backing up ' + data.tableName);
-    console.log(data.error);
+    console.log('Error backing up ' + data.table);
+    console.log(data.err);
 });
 
-backup.on('start-backup', function(tableName) {
+backup.on('start-backup', function(tableName, startTime) {
     console.log('Starting to copy table ' + tableName);
 });
 
-backup.on('end-backup', function(tableName) {
+backup.on('end-backup', function(tableName, backupDuration) {
     console.log('Done copying table ' + tableName);
 });