[pgp] Add compatibility for Gajim 1.1
This is a continuation of commit 97c2bfb "Add compatibility for Gajim 1.1".
Without this fix my Gajim refuses to start:
Traceback (most recent call last):
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/application.py", line 221, in _activate
self.interface.run(self)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/gui_interface.py", line 2541, in run
app.plugin_manager = plugins.PluginManager()
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/helpers.py", line 129, in __call__
cls.instance = super(Singleton, cls).__call__(*args, **kwargs)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/pluginmanager.py", line 116, in __init__
self.add_plugins(pc)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/helpers.py", line 114, in wrapper
result = f(*args, **kwargs)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/pluginmanager.py", line 224, in add_plugins
self.add_plugin(plugin_class)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/helpers.py", line 114, in wrapper
result = f(*args, **kwargs)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/pluginmanager.py", line 182, in add_plugin
plugin = plugin_class()
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/helpers.py", line 108, in wrapper
result = f(*args, **kwargs)
File "/home/pitchum/code/pub/gajim-family/gajim/gajim/plugins/gajimplugin.py", line 178, in __init__
self.init()
File "/home/pitchum/.local/share/gajim/plugins.test/pgp/pgpplugin.py", line 68, in init
self.description = _('PGP encryption as per XEP-0027')
NameError: name '_' is not defined