UrlShortenerPlugin. Fix deactivation

url_shortener/manifest.ini

@@ -1,7 +1,7 @@
 [info]
 name: Url Shortener
 short_name: url_shortener
-version: 0.3.3
+version: 0.3.4
 description: Plugin that allows users to shorten a long URL in messages.
  For example, you can turn this link:
  https://trac.gajim.org/timeline

url_shortener/url_shortener.py

@@ -110,6 +110,8 @@ class Base(object):
         self.chat_control.handlers[self.id_] = self.textview.tv
 
     def print_special_text(self, special_text, other_tags, graphics=True):
+        if not self.plugin.active:
+            return
         is_xhtml_link = None
         text_is_valid_uri = False
         buffer_ = self.textview.tv.get_buffer()