Add new VERSION command

[gjwgit]

Currently --version will report the package version when the argument to ml is a package name

$ ml bing --version
bing version 0.1.0

I think this is the only ml command that allows the package name as the first parameter. This exception to the general rule is problematic.

Add a new mlhub command, VERSION, to report the package version.

Without a package name it should report the mlhub version.

$ ml version bing
bing version 0.1.0

$ ml version
mlhub version 3.8.4

[gjwgit]

Also, remove "-v" but keep "--version" for the mlhub command. This then allows "-v" to be utilised by packages, for example, as a shortcut for --verbose.