Version 1.2.7

Updated allowed nos to the following

 supported_nos = {'aireos',
                  'apic',
                  'asa',
                  'bigip',
                  'cheetah',
                  'comware',
                  'dnac',
                  'gaia',
                  'ios',
                  'iosxe',
                  'iosxr',
                  'ironware',
                  'junos',
                  'linux',
                  'nxos',
                  'sros',
                  'viptela'}