Use consistent quote in locale yaml.

config/locales/en.yml

@@ -1,13 +1,13 @@
 en:
   devise:
     failure:
-      invited: 'You have a pending invitation, accept it to finish creating your account.'
+      invited: "You have a pending invitation, accept it to finish creating your account."
     invitations:
-      send_instructions: 'An invitation email has been sent to %{email}.'
-      invitation_token_invalid: 'The invitation token provided is not valid!'
-      updated: 'Your password was set successfully. You are now signed in.'
+      send_instructions: "An invitation email has been sent to %{email}."
+      invitation_token_invalid: "The invitation token provided is not valid!"
+      updated: "Your password was set successfully. You are now signed in."
       no_invitations_remaining: "No invitations remaining"
-      invitation_removed: 'Your invitation was removed.'
+      invitation_removed: "Your invitation was removed."
       new:
         header: "Send invitation"
         submit_button: "Send an invitation"
@@ -16,8 +16,8 @@ en:
         submit_button: "Set my password"
     mailer:
       invitation_instructions:
-        subject: 'Invitation instructions'
-        hello: 'Hello %{email}'
-        someone_invited_you: 'Someone has invited you to %{url}, you can accept it through the link below.'
-        accept: 'Accept invitation'
+        subject: "Invitation instructions"
+        hello: "Hello %{email}"
+        someone_invited_you: "Someone has invited you to %{url}, you can accept it through the link below."
+        accept: "Accept invitation"
         ignore: "If you don't want to accept the invitation, please ignore this email.<br />Your account won't be created until you access the link above and set your password."