fix bug 570392, command help traceback

As a consequence of using doc=_('some message') the _()
method was returning a Gettext instance, thus when optparse
was handed the help text it received a Gettext instance instead
of a basestring. optparse tried to operate on the Gettext instance
as if it were a basestring and since it wasn't threw an exception.
The fix is to promote (e.g. cast) the option.doc to unicode.
If the option.doc was a str it becomes unicode, if it was unicode
nothing happens, if it was Gettext (or any other object implementing
the __unicode__() method) object is converted to unicode via the
objects rules.

By the way, while debugging this I discovered strings which were not
localized, sometimes option.doc would be a str and sometimes a Gettext
object. In a subsequent patch I'll fix all those unlocalized doc
strings, but I don't want to bury this fix along with a load of
string fixes.

ipalib/cli.py

@@ -828,7 +828,7 @@ class cli(backend.Executioner):
         for option in cmd.options():
             kw = dict(
                 dest=option.name,
-                help=option.doc,
+                help=unicode(option.doc),
             )
             if option.password and self.env.interactive:
                 kw['action'] = 'store_true'