Fix UI bug introduced in #244.

The 'duration' field was incorrectly renamed to 'task time' in the table that
lists stages.
Revert "Fix one unit test that was not setting spark.cleaner.ttl"

This reverts commit 942c80b34c4642de3b0237761bc1aaeb8cbdd546.
Revert "Fix default TTL for metadata cleaner"

This reverts commit 669ba4caa95014f4511f842206c3e506f1a41a7a.
Merge pull request #393 from pwendell/revert-381

Revert PR 381

This PR missed a bunch of test cases that require "spark.cleaner.ttl". I think it is what is causing test failures on Jenkins right now (though it's a bit hard to tell because the DNS for cs.berkeley.edu is down).

I'm submitting this to see if it fixes jeknins. I did try just patching various tests but it was taking a really long time because there are a bunch of them, so for now I'm just seeing if a revert works.
Merge pull request #388 from pwendell/master

Fix UI bug introduced in #244.

The 'duration' field was incorrectly renamed to 'task time' in the table that
lists stages.