This test is redundant, now.
NaN suggests there was an error estimating the file. We should only hide the button if we know it has a size of 0.
tidy of conditions in addDownloadEstimate
Merge branch 'master' into downloadEstimatorPotentialBugFix_takeToo

Conflicts:
	web-app/js/portal/cart/DownloadEstimator.js
Merge pull request #1280 from aodn/downloadEstimatorPotentialBugFix_takeToo

Download estimator potential bug fix take too