`lpad admin` gives python errors when used without sub command

[zhubonan]

lpad admin command, when enterred without any sub-command will give an error like:

Traceback (most recent call last):
  File "/home/bonan/miniconda3/envs/fireworks/bin/lpad", line 11, in <module>
    load_entry_point('FireWorks', 'console_scripts', 'lpad')()
  File "/home/bonan/appdir/fireworks/fireworks/scripts/lpad_run.py", line 1431, in lpad
    args.func(args)
AttributeError: 'Namespace' object has no attribute 'func'

Whereas I think it should print the help information instead.

usage: lpad admin [-h] {maintain,orphaned,tuneup,refresh,unlock} ...

optional arguments:
  -h, --help            show this help message and exit

action:
  {maintain,orphaned,tuneup,refresh,unlock}
    maintain            Run database maintenance
    orphaned            Find orphaned FireWorks
    tuneup              Tune-up the database (should be performed during scheduled downtime)
    refresh             manually force a workflow refresh (not usually needed)
    unlock              manually unlock a workflow that is locked (only if you know what you are doing!)

This should be an easy fix for someone know the lpad script. Unfortunately, I cannot get my head around the argument parsers....