feature(report): allow use of --last_month when generating reports

Author: denefoster

src/gtt-report.js

@@ -42,6 +42,7 @@ program
     .option('--today', 'ignores --from and --to and queries entries for today')
     .option('--this_week', 'ignores --from and --to and queries entries for this week')
     .option('--this_month', 'ignores --from and --to and queries entries for this month')
+    .option('--last_month', 'ignores --from and --to and queries entries for last month')
     .option('-c --closed', 'include closed issues')
     .option('-m --milestone <milestone>', 'include issues from the given milestone')
     .option('--hours_per_day <hours>', 'hours per day for human readable time formats')
@@ -168,6 +169,10 @@ if (program.opts().this_month)
     config
         .set('from', moment().startOf('month'))
         .set('to', moment().endOf('month'));
+if (program.opts().last_month)
+    config
+        .set('from', moment().subtract(1, 'months').startOf('month'))
+        .set('to', moment().subtract(1, 'months').endOf('month'));
 
 Cli.quiet = config.get('quiet');
 Cli.verbose = config.get('_verbose');