Offline participation: implement completed puzzle methods

config/locales/en.yml

@@ -116,6 +116,8 @@ en:
               not_a_csv_file: "it must be a CSV file"
         offline:
           attributes:
+            end_image:
+              blank: Please upload an image
             name:
               blank: Please enter a name for your participation
             start_image:
@@ -218,6 +220,7 @@ en:
       create: "Create"
       delete: "Delete"
       edit: "Edit"
+      end: Click here to submit your completion
       export: Export
       import: CSV Import
       open: Open
@@ -242,7 +245,8 @@ en:
     settings: Settings
     log_out: Log out
   offlines:
-    start_image_select: Enter your photo of the puzzle with the provided code written on a paper before starting it
+    end_image_select: Take a photo of your completed puzzle
+    start_image_select: Take a photo of the puzzle with the provided code written on a paper before starting it
   puzzles:
     destroy:
       notice: Puzzle deleted