Merge branch 'first-gosdn-code' into 'master'

.gitignore

Programming.md

cliInterface/gosdnCLI.proto

gosdn-cli/gosdn-cli.go

main.go

nucleus/controller.go

nucleus/nucleus-core.go

nucleus/root.go

yang-processor/gosdn.go

yang-processor/gosdnyang.go.go

yang/iana-if-type.yang

yang/ietf-inet-types.yang

yang/ietf-interfaces.yang

yang/ietf-yang-types.yang

yang/openconfig-extensions.yang

yang/openconfig-if-aggregate.yang

yang/openconfig-if-ethernet.yang

yang/openconfig-if-ip-ext.yang

yang/openconfig-if-ip.yang

yang/openconfig-interfaces.yang