Before this commit, we held onto *cobra.Command objects,
but that is not actually supported: after the first Execute(),
commands like updateCmd are stuck on the first-ever provided ctx.
Instead, turn command initialization into functions.
I only noticed this when trying to do two 'gok update'
from within the same test, where the fake build timestamp
is injected via the context (the timestamp was always the same).
This interfaces with spf13/cobra without typing ourselves to its types, and
exerting control (for better of for worse) about what aspects one can control.
With this, we can move the code in cmd to internal/
