added arista models and ciena reposes

models/ciena-6500-adjacencies.yang

models/ciena-6500-alarms.yang

models/ciena-6500-almprofile.yang

models/ciena-6500-ampmons.yang

models/ciena-6500-amps.yang

models/ciena-6500-application.yang

models/ciena-6500-channel-control.yang

models/ciena-6500-comms.yang

models/ciena-6500-cpu.yang

models/ciena-6500-debuglog.yang

models/ciena-6500-diagnostic.yang

models/ciena-6500-disps.yang

models/ciena-6500-encryption.yang

models/ciena-6500-enums.yang

models/ciena-6500-equipment-status.yang

models/ciena-6500-equipment.yang

models/ciena-6500-events.yang

models/ciena-6500-idlers.yang

models/ciena-6500-install.yang

models/ciena-6500-l2services.yang