Updated forgot_password()

If identity is set to username it was showing invalid email address. So the modified code first checks if the identity in ion config file is set to "username" or "emai"l. If it is set to "username" we can't set the validation rule of valid_email.
Merge pull request #634 from toton333/2

Updated forgot_password()
Updated forgot_password()

Added proper error message display. If identity is set to username, and form is submitted without username it used to show " the email field is required". So code is modified to show the proper identity label.
Merge pull request #635 from toton333/2

Updated forgot_password()
Updated forgot_password()

If there is no such username in the database the modified code shows the error message according to the identity set in the ion config file.
Previously it used to show "No record of that email address." regardless of what identity set it uses.
Merge pull request #636 from toton333/2

Updated forgot_password()
Translate for default_group
Merge pull request #637 from gremboloid/patch-1

Translate for default_group
Added loading of database library to the example controller

Resolves issue #260