Password reset

Fixes #51 , added ability for users to reset forgotton passwords.

* Create user token for password reset
* Use token in email to ensure user is authorized to reset password
* Change password and delete token

A new configuration variable has been added to the dist file to allow changing the sending e-mail address:

`$config['website']['email'] = 'test@example.com';

This also includes two new template files

* `templates/mail/body.tpl`
* `template/mail/subject.tpl`

Those can be adjusted a bit to match your need.