CLI doesn't complain when given unknown deployments, pods, or paths

[wmorgan]

For tap and stat, and maybe other commands, specifying a non-existing deployment or pod doesn't result in any kind of error message.

E.g. stat:

william:~/devel/conduit$ conduit stat deploy default/hello
NAME            REQUEST_RATE   SUCCESS_RATE   P50_LATENCY   P99_LATENCY
default/hello         2.5rps         96.00%         352ms         875ms
william:~/devel/conduit$ conduit stat deploy default/hello2
NAME   REQUEST_RATE   SUCCESS_RATE   P50_LATENCY   P99_LATENCY

and tap:

william:~/devel/conduit$ conduit tap deploy default/hello
[172.17.0.3:53280 -> 172.17.0.11:80]
HTTP Request
Stream ID: (0, 263)
HTTP POST world.default.svc.cluster.local/helloworld.World/Greeting
...
^C
william:~/devel/conduit$ conduit tap deploy hello
^C

This isn't too bad on its surface, but a) it means that e.g. forgetting to put the namespace for tap deploy means that the command just hangs forever (this is an easy mistake, and we had a user confused about this in #conduit today), and b) it doesn't match how kubectl works, e.g.

william:~/devel/conduit$ kubectl get -n conduit deploy/prometheus
NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
prometheus   1         1         1            1           7d
william:~/devel/conduit$ kubectl get -n conduit deploy/prometheus2
Error from server (NotFound): deployments.extensions "prometheus2" not found

I think these commands should return an error if the specifying pod, deployment, or path (maybe?) is not found.

[siggy]

This issue is two-thirds resolved.

tap

will be fixed in #827

conduit tap continues to exhibit this behavior.

$ conduit tap deploy foo
...

stat

stat was fixed in #760:

$ conduit stat deploy emoji
Error: error calling stat with request: deployment.apps "emoji" not found
Usage:
  conduit stat [flags] RESOURCETYPE [RESOURCENAME]

get

conduit get no longer supports resources as input:

$ conduit get emojivoto/web-b8f8786b8-49d9j
Error: invalid resource type emojivoto/web-b8f8786b8-49d9j, only pods are allowed as resource types
Usage:
  conduit get [flags] pods

[siggy]

Resolved in #827.