Add pop-up for the password recovery page

Steps to reproduce:
1. Click on 'Sign In' link
2. Click on 'Forgot password?' link
3. Enter the email used for registration
4. Click on 'Send' button

Actual result: User sees message "Email has been sent, please check your inbox for the new password", but  'Send' button  is still shown and active; it is possible to send password again by clicking on it.

Expected result: Pop-up dialog with just OK button opens with  message
"Email has been sent, please check your inbox for the new password."
Start forum page is opened after clicking on OK button.