Support unshortlisting for a project.

app/messages/__init__.py

@@ -2,6 +2,7 @@ from .message_builders import (
     login_manager_message,
     login_unsuccessful_error,
     project_not_found,
+    shortlist_not_found,
 )
 
 #########################################################################
@@ -12,3 +13,4 @@ LOGIN_UNSUCCESSFUL_ERROR = login_unsuccessful_error()
 LOGIN_MANAGER_MESSAGE = login_manager_message()
 
 PROJECT_NOT_FOUND = project_not_found()
+SHORTLIST_NOT_FOUND = shortlist_not_found()