Bug 1069962: add strings that will be used for the Gravatar permission promo box. r=Standard8

browser/locales/en-US/chrome/browser/loop/loop.properties

@@ -169,6 +169,14 @@ audio_call_menu_button=Audio Conversation
 ## https://people.mozilla.org/~dhenein/labs/loop-mvp-spec/#contacts
 video_call_menu_button=Video Conversation
 
+## LOCALIZATION NOTE(gravatars_promo_message): The {{learn_more}} part will be
+## replaced with a link with the text content of gravatars_promo_message_learnmore.
+gravatars_promo_message=You can automatically add profile icons to your contacts \
+  by sharing their email addresses with Gravatar. {{learn_more}}.
+gravatars_promo_message_learnmore=Learn more
+gravatars_promo_button_nothanks=No Thanks
+gravatars_promo_button_use=Use Profile Icons
+
 # Conversation Window Strings
 
 initiate_call_button_label2=Ready to start your conversation?