pkg.list_available

Command:
```
[root@manage srv]# salt app.0.uswest2a.production.lhn pkg.available_version firefox
app.0.uswest2a.production.lhn:
    The minion function caused an exception: Traceback (most recent call last):
      File "c:\salt\bin\lib\site-packages\salt\minion.py", line 1036, in _thread_return
        return_data = func(*args, **kwargs)
      File "c:\salt\bin\lib\site-packages\salt\modules\win_pkg.py", line 102, in latest_version
        latest_available = _get_latest_pkg_version(pkg_info)
      File "c:\salt\bin\lib\site-packages\salt\modules\win_pkg.py", line 987, in _get_latest_pkg_version
        return sorted(pkginfo, cmp=_reverse_cmp_pkg_versions).pop()
    IndexError: pop from empty list
```

master error log:
```
015-11-09 21:07:47,169 [salt.master      ][ERROR   ][31723] Received minion error from [app.0.uswest2a.production.lhn]: The minion function caused an exception
```

minion error log:
```
2015-11-09 21:07:25,500 [salt.minion      ][INFO    ][10276] Starting a new job with PID 10276
2015-11-09 21:07:25,501 [salt.fileclient  ][INFO    ][10276] Caching directory 'win/repo-ng/' for environment 'base'
2015-11-09 21:07:25,649 [salt.minion      ][WARNING ][10276] The minion function caused an exception
2015-11-09 21:07:25,694 [salt.minion      ][INFO    ][10276] Returning information for job: 20151109210746988709
```