By default binary built through 'go get github.com/minio/mc'. Will be
considered UNOFFICIAL.GOGET with not versioning, 'go get' binaries
cannot use 'mc update' functionality.
First reasoning towards this is - go build tools have no way to specifying
versions and releases unlike `npm`. For this reason alone we have to
differentiate OFFICIAL and UNOFFICIAL.
Now a 'make' will build appropriate binaries, while 'go get' becomes UNOFFICIAL.
