Allow parameters for upgrade and uninstall

[technosophos]

The upgrade and uninstall commands currently do not let you specify parameters.

[squillace]

as of 48dbf3c, they do, but they throw errors:

duffle uninstall hellohelm-secondcreds -c hellohelm                                                                                                                   ✔  4693  21:49:40
Executing uninstall action...
[== Hi Duffle user ==]
uninstall action
Error: could not get Kubernetes config for context "": Error loading config file "/root/.kube/config": couldn't get version/kind; json parse error: json: cannot unmarshal string into Go value of type struct { APIVersion string "json:\"apiVersion,omitempty\""; Kind string "json:\"kind,omitempty\"" }
Action uninstall complete for hellohelm-secondcreds

I can assure you that cred set isn't empty:

duffle credentials show hellohelm                                                                                                                                     ✔  4697  21:54:20
name: hellohelm
credentials:
- destination:
    path: /root/.kube/config
  name: kubeconfig
  source:
    value: $HOME/.kube/config