[geary] Add new translatable developer name and translation comments to appdata.

[Michael Gratton <mjog src gnome org>]

commit 25e23b05fbfcef85ae01cdb24b8d056495725672
Author: Michael James Gratton <mike vee net>
Date:   Tue Sep 26 22:55:57 2017 +1000

    Add new translatable developer name and translation comments to appdata.

 desktop/org.gnome.Geary.appdata.xml.in |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/desktop/org.gnome.Geary.appdata.xml.in b/desktop/org.gnome.Geary.appdata.xml.in
index 7912aa2..4efbff6 100644
--- a/desktop/org.gnome.Geary.appdata.xml.in
+++ b/desktop/org.gnome.Geary.appdata.xml.in
@@ -7,7 +7,11 @@
   <project_license>LGPL-2.1+</project_license>
   <update_contact>geary-list gnome org</update_contact>
 
+  <!-- Translators: The application name -->
   <_name>Geary</_name>
+  <!-- Translators: The development team's name -->
+  <_developer_name>Geary Development Team</_developer_name>
+  <!-- Translators: The application's summary / tagline -->
   <_summary>Send and receive email</_summary>
   <description>
     <_p>
@@ -39,10 +43,12 @@
 
   <screenshots>
     <screenshot>
+      <!-- Translators: A screenshot description. -->
       <_caption>Geary displaying a conversation</_caption>
       <image type="default" width="1600" 
height="900">https://wiki.gnome.org/Apps/Geary?action=AttachFile&amp;do=get&amp;target=geary-conversation-0.12.png</image>
     </screenshot>
     <screenshot>
+      <!-- Translators: A screenshot description. -->
       <_caption>Geary showing the rich text composer</_caption>
       <image type="source" width="1600" 
height="900">https://wiki.gnome.org/Apps/Geary?action=AttachFile&amp;do=get&amp;target=geary-composer-0.12.png</image>
     </screenshot>