Removes Java option from HTML interface served by NDT sliver (#73)

[stephen-soltesz]

• Removes Java and WebSocket test buttons from HTML interface, such that all tests are WebSocket (if available) and only a 'Start Test' button.

• Eliminate a useless function, don't even append the Java applet to the DOM, and don't initialize the test if WebSocket support isn't detected.

• Eliminates an unused variable, eliminates a useless function, and fixes some typos.

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This change is 

[stephen-soltesz]

@nkinkade added as original author.

@pboothe added as maintainer of upstream relationship. Speaking of which when was the last time we sync'd with upstream?

[stephen-soltesz]

Builds are failing due to dependency on an old version of builder image without Go. I'll fix it in the morning.

[nkinkade]

I didn't go over every last detail of this PR with a fine-toothed comb because whenever I created this branch we are merging from, I had tested all the changes in the testbed and they worked as intended. The changes all look in line with what I remember doing all that time ago. :) In the odd event that something is broken, testbed e2e testing will catch it.

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Reviewed 3 of 3 files at r1. Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable

[stephen-soltesz]

Builds are failing due to dependency on ndt-support dev branch.

Builds do not test the current version of ndt sources. :-/

I'm sorting this out.

[stephen-soltesz]

Travis build is still failing even though the m-lab/ndt is fixed in master. Not sure how to trick it into syncing again. Closing this PR and re-opening.

[stephen-soltesz]

HAHA, success!

[stephen-soltesz]

@pboothe I don't think you'll object, so I'm proceeding TBR.