Offer more information in dnx --version

[troydai]

This is what we have today:

$ dnx --version
1.0.0-beta4-11309

It would be nice to print the full name so as to know what platform, arch and target framework the current dnx is for.

[davidfowl]

@troydai or @BrennanConroy can you work on this? It would be great since we have all flavors working in some form.

[troydai]

I'll take a look at it today.

[troydai]

I'll try to put the full build version in the AssemblyInformationVersionAttribute