[backport] PR #6792 to 4.2

[elastic-jasper]

Backport PR #6792

Commit 1:
Update selenium from 2.48.2 to 2.53.0 to work with latest Firefox 45.0.1

• Original sha: 81821fc
• Authored by LeeDr lee.drengenberg@elastic.co on 2016-04-05T20:46:06Z

Commit 2:
Update downloadSelenium to match version in intern.js.

• Original sha: 431fe52
• Authored by LeeDr lee.drengenberg@elastic.co on 2016-04-06T12:36:06Z

Commit 3:
Add selenium-server-standalone jar md5.

• Original sha: 4002140
• Authored by LeeDr lee.drengenberg@elastic.co on 2016-04-06T13:46:17Z

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Backported based on diff from PR #6802

[LeeDr]

The test on Jenkins failed before it got to the point of this change, downloading Selenium. So I think this PR is blocked.

[epixa]

I think the builds are broken on 4.2 for entirely different reasons. We'll probably never need to touch 4.2 again, which is why we aren't bothering fixing the builds.

Given that this change has gone green everywhere else, I'd recommend just pushing it directly to 4.2 and closing this PR.

[rashidkpc]

@LeeDr @epixa what do you want to do with this? We're not likely cutting another 4.2 release as court noted, so don't invest any time in making this work

[LeeDr]

@epixa suggested I go ahead and merge it, and I agree, but the merge button is grayed-out. I can use command line from my end but I have a couple of other changes in progress and didn't want to switch off of those right now. OK if I merge this later?

[epixa]

I got you covered - I manually pushed this to 4.2.

[LeeDr]

Thanks !

[epixa]

Whoops, correction... I thought I manually pushed it. We're good now.