[FixRM #7673] "Failed to reload" error.

When db_disconnect is issued, this funtion does not update the status of self.migrated to false.  So when another reload command is used, the update_module_details function will still try to connect to the database, which causes the "Failed to reload" error.

Please see the following ticket for more info:
http://dev.metasploit.com/redmine/issues/7673