* 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.
Automatic merge from submit-queue
Cleanup pkg/kubectl
I was reading through `pkg/kubectl` in preparation for completing https://github.com/kubernetes/kubectl/issues/11 and noticed several opportunities for improvement. This should be easy to review since it's mostly mechanical changes. The only complicated changes are in `addFromEnvFile`, which I refactored into two functions and wrote tests for.
**Release note**:
```release-note
NONE
```
updating with PR changes requested.
latest changes to having short for human readable only, and error cases moved a bit to the end.
rebase fixes
latest pr. changes.
small change moving return nil out of switch.
updated the nil check for the error in the humanreadable case.
more optimization in humanreadable code.
pushed up current test changes, this is purely temporary
finished writing tests
updated test and function names.
changed output extensions from .sh to output.
updated version, version struct now just called Version and not VersionObj.
made a few changes to testing.
fixed testing issues, created better test and cleanup
go format change.
The clientset will throw an error for aggregated apiservers because the
clientset looks for specific versions of apis that are compiled into
the client. These will be missing from aggregated apiservers.
The discoveryclient is fully dynamic and does not rely on compiled
in apiversions.
The kubectl version output is very complex and makes it hard for users
and vendors to give actionable information. For example during the
recent Kubernetes 1.4.3 TLS security scramble I had to write a one-liner
for users to get out the version number to give to figure out if they
are vulnerable:
$ kubectl version | grep -i Server | sed -n 's%.*GitVersion:"\([^"]*\).*%\1%p'
Instead this patch outputs simply output with `--short`
./kubectl version --short
Client Version: v1.4.3
Server Version: v1.4.3
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