obj.UrlLead: add url as leaf alias; use url for name when name is none

This patch allow to search leaves by matching also url - not only title.

Closes: lp#516426
firefox: set uri as title when title is null

For some bookmarks there is no title - only "null" value.
firefox: support tags as subcatalogs of firefox
Updated German translation
gtg: update api - support GTG 0.2.9

+ support new api (CamelCase naming)
core: Fix urlparse usage for Python 2.7.3

Python 2.7.3 drops urlparse.uses_fragment global that we monkeypatched.
In hindsight, it never was really necessary. uses_netloc which we still
use is tricker to fix.

This lets Kupfer work with 2.7.3 again.

Co-authored-by: Karol Będkowski

Launchpad-bug: https://bugs.launchpad.net/kupfer/+bug/1014502/
Merge remote-tracking branch 'karol/bugs/lp1014378_gtg'

* karol/bugs/lp1014378_gtg:
  gtg: update api - support GTG 0.2.9
Handle Telepathy (dbus) exception

`dbus.exceptions.DBusException: org.freedesktop.Telepathy.Error.NotImplemented:
No properties known for interface org.freedesktop.Telepathy.Channel.Interface.Group`
Handle rogue jabber servers that offer no presence information.
empathy: Properly check exception if Empathy is not installed/available
contrib: Remove twitter plugin

The twitter plugin is unlikely to be revived. If you want it, get it
from Kupfer's git history.
wscript: Remove recommendation for 'gnome' module

The 'gnome' module is only relevant for Gnome 2.24 and desktops that
implement X Session Manager protocol (but not needed for Xfce and
Gnome).
extras: Remove Nautilus Selected File plugin (kupfer_provider.py)

Never updated for Nautilus 3.x. At the moment support Copy/Paste to
aquire files from the file manager instead.
nautilusselection: Move to contrib/
tracker: Move tracker 0.6 plugin to contrib/
po: Update sv. Update POTFILES.in
dbuscompat: Remove executable bit on file
commandexec: Remove deprecated location for module
Merge remote-tracking branch 'karol/bugs/lp516426_firefox_title'

* karol/bugs/lp516426_firefox_title:
  firefox: support tags as subcatalogs of firefox
  firefox: set uri as title when title is null
  obj.UrlLead: add url as leaf alias; use url for name when name is none
Support Konsole as a terminal emulator.

Launchpad-bug: https://bugs.launchpad.net/kupfer/+bug/919347