Stop using max_password_length config option

Ion Auth 3 has deprecated the `max_password_length` config option (and
rightfylly so). Remove any references to it in our code. This fixes an
issue where password could not be changed or reset because they had to
be shorter than a `max_password_length` value that was not set.

Resolves #115

application/controllers/Auth.php

@@ -137,7 +137,7 @@ function logout()
 	function change_password()
 	{
 		$this->form_validation->set_rules('old', 'Old password', 'required');
-		$this->form_validation->set_rules('new', 'New Password', 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|max_length[' . $this->config->item('max_password_length', 'ion_auth') . ']|matches[new_confirm]');
+		$this->form_validation->set_rules('new', 'New Password', 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|matches[new_confirm]');
 		$this->form_validation->set_rules('new_confirm', 'Confirm New Password', 'required');
 
 		if (!$this->ion_auth->logged_in())
@@ -248,7 +248,7 @@ public function reset_password($code = NULL)
 		if ($user)
 		{  //if the code is valid then display the password reset form
 
-			$this->form_validation->set_rules('new', 'New Password', 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|max_length[' . $this->config->item('max_password_length', 'ion_auth') . ']|matches[new_confirm]');
+			$this->form_validation->set_rules('new', 'New Password', 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|matches[new_confirm]');
 			$this->form_validation->set_rules('new_confirm', 'Confirm New Password', 'required');
 
 			if ($this->form_validation->run() == false)
@@ -400,7 +400,7 @@ function create_user()
 		$this->form_validation->set_rules('phone2', 'Second Part of Phone', 'required|xss_clean|min_length[3]|max_length[3]');
 		$this->form_validation->set_rules('phone3', 'Third Part of Phone', 'required|xss_clean|min_length[4]|max_length[4]');
 		$this->form_validation->set_rules('company', 'Company Name', 'required|xss_clean');
-		$this->form_validation->set_rules('password', 'Password', 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|max_length[' . $this->config->item('max_password_length', 'ion_auth') . ']|matches[password_confirm]');
+		$this->form_validation->set_rules('password', 'Password', 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|matches[password_confirm]');
 		$this->form_validation->set_rules('password_confirm', 'Password Confirmation', 'required');
 
 		if ($this->form_validation->run() == true)