Issue #4 , #5 , #6 and #7

For issue #4:
- removed fill_table__server_status()
- removed ADMIN_SQLITE_TABLE_MYSQL_SERVER_STATUS
- fixed ADMIN_SQLITE_TABLE_MYSQL_SERVER

For issue #5:
- created functions __insert_or_ignore_maintable_select_disktable() , __delete_disktable() , __insert_or_replace_disktable_select_maintable() and __attach_configdb_to_admindb()

For issue #6 and #7:
- table ADMIN_SQLITE_TABLE_MYSQL_USERS has fields use_ssl, backend and frontend