Use absolute imports on all plugins

This is necessary because Gajim is with 0.16.11 a python package

length_notifier/length_notifier.py

@@ -29,9 +29,9 @@ import sys
 from gi.repository import Gtk
 from gi.repository import Gdk
 
-from plugins import GajimPlugin
-from plugins.helpers import log, log_calls
-from plugins.gui import GajimPluginConfigDialog
+from gajim.plugins import GajimPlugin
+from gajim.plugins.helpers import log, log_calls
+from gajim.plugins.gui import GajimPluginConfigDialog
 
 class LengthNotifierPlugin(GajimPlugin):
 

length_notifier/manifest.ini

@@ -1,8 +1,8 @@
 [info]
 name: Message Length Notifier
 short_name: length_notifier
-version: 0.2
+version: 0.3
 description: Highlights message entry field in chat window when given length of message is exceeded.
 authors = Mateusz Biliński <mateusz@bilinski.it>
 homepage = http://trac-plugins.gajim.org/wiki/LengthNotifierPlugin
-min_gajim_version: 0.16.10
+min_gajim_version: 0.16.11