Update openbsdpkg.py
Update openbsdpkg.py

* It looks like function 'pkg_resource.compare' used in orig. file is obsolete, 
* change correcting following exception, when comparing currently installed and latest available package versions: 

~~~ 
   The minion function caused an exception: Traceback (most recent call last):
      File "/usr/local/lib/python2.7/site-packages/salt/minion.py", line 1161, in _thread_return
        return_data = func(*args, **kwargs)
      File "/usr/local/lib/python2.7/site-packages/salt/modules/openbsdpkg.py", line 108, in latest_version
        if not cur or __salt__['pkg_resource.compare'](pkg1=cur,
      File "/usr/local/lib/python2.7/site-packages/salt/utils/lazy.py", line 90, in __getitem__
        raise KeyError(key)
    KeyError: 'pkg_resource.compare'
~~
saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt