Optionally create jobs from XML config instead of Template Job

[mikeocool]

We had kind of an annoying problem that popped up when we upgrade Jenkins a few months ago; every time we pushed anything to any branch on our github repo, the Jennifer template job would start building, and then immediately fail and trigger failure notifications on our various reporters, since ${pr_branch} isn't a real branch.

I poked around in jenkins, the git plugin, and the github plugin trying to figure out how to make this stop, and it seemed like it was sort of intentional. Basically, because the git plugin can't determine if there are any changes (since ${pr_branch} doesn't exist), it says 'GAH! I can't tell if anything has changed, do a build!'

It seemed like a nice way to avoid this issue all together would be to just get rid of the the template job altogether, and create jobs from a template jenkins project XML file that lived outside of Jenkins, and thus this pull request born.

[lra]

@jamesob want to take a look at this?

[jamesob]

sure. checking it out now. don't have a test environment set up though...

[jamesob]

@mikeocool rad! this is a great change; thanks for sharing upstream.

I haven't tested this branch myself (no environment readily at hand), but nothing looks out of place after a few reads. @lra or @malford may want to test this on Percolate's environment.

It'd be really awesome to update README.md with information on how to use this new config option, and (potentially) a sample XML config file?

[lra]

Cool,
@mikeocool feel like helping with this (README + sample XML)?
@malford can you test this out?

[mikeocool]

Yeah, I'll definitely add a sample XML and update the README shortly.

[malford]

@lra Sure, will test this out this week.