Add container image validation

[f-higashi]

Added container image validation. #422

Image reference format is very complicated. I think it is hard to write and maintain it.
So I used docker library in backend.

What do you think?

@bryk

BTW
How do I update Godep.json?
When I executed 'godep save ./src/app/backend', all dependencies are removed.

[bryk]

@maciaszczykm You've recently updated Godeps. Can you help @f-higashi with this?

[maciaszczykm]

@bryk @f-higashi I can do it on Monday, because till end of the week I'm on sick leave.

[bryk]

@f-higashi

Try:

• 'godep restore ./src/app/backend'
• Then go get ... deps that you want to update
• 'godep save ./src/app/backend'

[f-higashi]

Thanks for information.
Sorry. My repository path and GOPATH was wrong.

[f-higashi]

Hmm.
Travis build does not start.
In my repository travis build works.

@bryk
Do you have an idea?
or
Can you cancel the following build? This build process task is broken?

• https://travis-ci.org/kubernetes/dashboard/builds/113315560

[bryk]

I've cancelled the build.

[bryk]

Let me know when this is ready for review.

[f-higashi]

Thank you to cancel jobs.
But travis build does not start too.
Hmm..

[bryk]

Hmm.... I dont know. Maybe drop this PR and create a new one?

[f-higashi]

Yes.
It's better.
Please cancel existing build job.

[f-higashi]

After closing this pull request, the build started...
It's strange.
I open this.

[f-higashi]

After reopen, new build is registered and stopped.
I'll create new pull request.