Use ksonnet CLI instead of ksonnet libs (#590)

[merenbach]

Closes #590.

Major points:

• Completely removes the Ksonnet client libs as a dependency.
• Removes the ksonnetApp struct and KsonnetApp interface types and replaces with utility functions that accept a root dir path.
• Upgrades to Ksonnet 0.13.0, which purports to fix v0.12 Regression: param values with double quotes are unexpectedly escaped ksonnet/ksonnet#861 (which prevented us from upgrading to 0.12.0). @jessesuen I have tested the new version and it appears to satisfy the repro tests you put into the bug you submitted, so I am so far satisfied that the issue with 0.12.0 is resolved.

Other points:

• Replaces use of path lib with filepath since we're working with file paths, not just serialized object paths.

[jessesuen]

Let's not mix yaml packages, everything else is using ghodss/yaml.

[jessesuen]

I still prefer keeping around the ksonnet interface, especially for mocking, and consistency with the helm and kustomize implementations. It can have a reduced method list, but theres value in having it defined as an interface.

[jessesuen]

Please don't add dependencies here -- it's stated clearly in the comment.

[jessesuen]

@merenbach i blew away my vendor directory, ran dep ensure and was able to build everything. I'm not sure what the problem could be.

[merenbach]

@jessesuen that's really interesting! Seems that @dthomson25 and I have some difference between our local setups and yours. I'm using the following Go version:

$ go version
go version go1.11 darwin/amd64

This is installed with Homebrew (brew install go), in case that makes any difference.

[jessesuen]

It seems all of the ksonnet methods have been switching to use a new package level ksCmd which accepts the ksonnet root as the first argument. The point of having a method-level ksCmd was so that the callers didn't have to keep passing the root dir. I don't think the package level ksCmd is necessary if the only reason it was made package-level was to be able to run ksonnet version without an app, in which case the KsonnetVersion() function could have been implemented using a throwaway app. e.g.:

ksApp := ksonnetApp{}	
ksApp.ksCmd("version")

[merenbach]

Testing update: am able to do a basic sync on the Ksonnet guestbook. I am also able set a JSON parameter override, e.g.:

  source:
    componentParameterOverrides:
    - component: ks-guestbook
      name: helloworld
      value: '{"A":"B","C":4}'
    environment: default
    path: ksonnet-guestbook
    repoURL: https://github.com/argoproj/argocd-example-apps.git
    targetRevision: HEAD

Also able to override images, e.g.,:

$ ./dist/argocd app create --name ks-guestbook --repo https://github.com/argoproj/argocd-example-apps.git --path ksonnet-guestbook --env default -p guestbook-ui=image=gcr.io/heptio-images/ks-guestbook-demo:0.7

Output:

  operationState:
    finishedAt: 2018-09-26T19:37:47Z
    message: successfully synced
    operation:
      sync:
        parameterOverrides:
        - component: guestbook-ui
          name: image
          value: gcr.io/heptio-images/ks-guestbook-demo:0.7
        syncStrategy:
          hook: {}
    phase: Succeeded
    startedAt: 2018-09-26T19:37:44Z
    syncResult:
      resources:
      - kind: Service
        message: service/ks-guestbook-ui created
        name: ks-guestbook-ui
        namespace: default
        status: Synced
      - kind: Deployment
        message: deployment.apps/ks-guestbook-ui created
        name: ks-guestbook-ui
        namespace: default
        status: Synced
      revision: d9c52b4c89474bf6f7c33694b7650e54b60944b4

Fixed issues presented so far

[alexmt]

One minor comment. LGTM after fixing it

[alexmt]

Default revision should be set before executing repoClient.GetFile (line 328)

[alexmt]

LGTM