Bug 17924 - Fix error in password recovery

Bug 17924 - Fix error in password recovery

To test:

- Set OpacResetPassword = allowed
- Make sure you have a user with a username and email
- Go to the OPAC and make sure you are not logged in
- Click on the "Forgot your password?" link
- Fill in "Login" and "Email" and click on "Submit"
- You will get an error that says:

Undefined subroutine &C4::Letters::GetPreparedLetter called at
/home/vagrant/kohaclone/Koha/Patron/Password/Recovery.pm line 142.

- Apply the patch
- The steps above will have added your user to the borrower_password_recovery
  table in the database. Delete it from there to make sure you start a
  fresh reset request.
- Repeat the steps above and notice that the error is gone. You should
  get a nice message instead that says "An email has been sent to [your
  email]".
- Sign off

Signed-off-by: Zoe Schoeler <crazy.mental.onion@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit b43b79156f179094ed16a896f0bf0b3d39b4af7d)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>