p1tr fails when 'wtf' executable is not in path

[Michael Otteneder]

Traceback (most recent call last):
  File "bot.py", line 58, in <module>
    main()
  File "bot.py", line 43, in main
    plugs = plugins.PluginLoader().load_plugins()
  File "/Users/mc/dev/p1tr/lib/plugins.py", line 34, in load_plugins
    mod_name.capitalize() + 'Plugin')())
  File "/Users/mc/dev/p1tr/plugins/unix.py", line 29, in __init__
    if self._get_output('wtf', False, False):
  File "/Users/mc/dev/p1tr/lib/plugin.py", line 109, in _get_output
    return bool(subprocess.Popen(command))
  File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/subprocess.py", line 593, in __init__
    errread, errwrite)
  File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/subprocess.py", line 1079, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory[21:30:07] INFO: None

[Michael Otteneder (m-otteneder)]

fixed via revision #123