[Qgis-tr] String update request due to Sextante renaming

[Artem Popov]

As Sextante has been renamed to Processing [1] and has been given its
own menu "Processing" in the primary menubar, new untranslatable
string now appears in the most inconvenient place in the GUI. It is
not acceptable for a localized UI to have main menus in English.
Werner, can you update the strings to include this recent changes?

[1] https://github.com/qgis/Quantum-GIS/commit/9bb3d6eb6b01321f33c30e66a8e48c0c94a61a98

Just in case another string update is gonna happen, translation files
can also benefit from pull requests [2] and [3] that still require
attention.

[2] https://github.com/qgis/Quantum-GIS/pull/815
[3] https://github.com/qgis/Quantum-GIS/pull/816


Cheers,
--Artem