Extensive build info

[martinda]

This PR adds the ability to read _class types of build actions. Jenkins can produce build actions in the build info that look like this:

{
  "actions" : [
    {
       "text" : "Hudson, we have a problem.",
       "iconPath" : "error.svg",
       "_class" : "com.jenkinsci.plugins.badge.action.BadgeSummaryAction"
    },
    {
       "_class" : "org.jenkinsci.plugins.displayurlapi.actions.RunDisplayAction"
    }
    ]
}

These are created by pipeline code such as:

createSummary("error.svg").appendText("Hudson, we have a problem.", false, false, false, "red")

With this PR, we can read these build actions in the BuildInfo.

[martinda]

I added mock and integration tests, they all pass using the docker container. I had to upgrade Jenkins so it could support an easy way to add build actions.

[cdancy]

LGTM. @martinda feel free to merge when you're ready.

[martinda]

@cdancy a new release would be much appreciated. Thanks!

[cdancy]

@martinda just released version 1.0.2. I'd give it a bit but it should be resolvable soon.