* Rename variables and functions to match Go convention.
For example, UsageError --> UsageErrorf.
* Remove redundant or unreachable code.
* Simplify some utility functions (no functionality changes).
* Fix hanging 'if { return } else { return }' constructs.
* Fix several incorrect printf verbs.
because the user may be trying to pipe the output of this command as
the input to another. This makes `set subject` and `set resources`
consistent with all similar commands in this directory.
Signed-off-by: Bryan Boreham <bryan@weave.works>
