* refactor nxos_ospf * refactor nxos_portchannel * refactor nxos_rollback * refactor nxos_switchport
* fix issues with python3.x * Add integration testa and fix for nxos_evpn_vni * add nxos_evpn_vni to nxos.yaml * fix get_vtp_config() * add new integration tests * fix rollback * add integration test files