Cannot pass arguments in "run" mode

[alexhudson]

The wrapper automatically passes arguments through to the runtime container, but in run mode it just drops them on the floor. Both should work the same way.

[alexhudson]

I now have a way of doing this, unfortunately it's a bit of a work-around. I want to be able to write:

stowage run basic-bash --version

... for example, but any options I pass get parsed by urfave/cli (see urfave/cli#663). However, this can be hacked around like this:

stowage run basic-bash -- --version

urfave/cli stops parsing at --, and if that is the first argument stowage finds, it simply drops it from the list, giving us the original list of arguments we wanted.

Leaving this open until we find a better way of doing it.