translation: add missing strings for sharing options

Share screen area and share screen are not translated.
Add them to the translation system.

Change-Id: Ia37b791c2c445a7fb447110c2cc99d686088c535
Tuleap: #45
diff --git a/po/POTFILES.in b/po/POTFILES.in
index e3dbf11..6bcd60c 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -18,6 +18,7 @@
 src/utils/menus.cpp
 src/ringmainwindow.cpp
 src/ringwelcomeview.cpp
+src/video/video_widget.cpp
 ui/accountadvancedtab.ui
 ui/accountaudiotab.ui
 ui/accountgeneraltab.ui