fixed bug: script arg is int will not work


salt 'minion1' cmd.script salt://scripts/test.sh '5156'
```
minion1:
    Missing arguments executing "cmd.script": ArgSpec(args=['source', 'args', 'cwd', 'runas', 'shell', 'env', 'template', 'umask'], varargs=None, keywords='kwargs', defaults=(None, None, None, '/bin/bash', 'base', 'jinja', None))
```
error like this:
```
Traceback (most recent call last):
  File "/usr/lib64/python2.6/multiprocessing/process.py", line 232, in _bootstrap
    self.run()
  File "/usr/lib64/python2.6/multiprocessing/process.py", line 88, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python2.6/site-packages/salt/minion.py", line 426, in _thread_return
    ret['return'] = func(*args, **kwargs)
  File "/usr/lib/python2.6/site-packages/salt/modules/cmdmod.py", line 487, in script
    path + ' ' + args if args else path,
TypeError: cannot concatenate 'str' and 'int' objects
```