Update aXe results

[selfthinker]

I have re-tested all of our test cases with aXe and updated the results accordingly. I tested with the aXe Chrome extension (version 3.1.1, released on 15 November 2017, which is using axe-core API version 2.4.0).

9 entries changed as a result of that:

• Changed from negative to positive ("not found" or "different issue found" vs "issue found" or "user to check")
  • html element has an empty lang attribute
  • empty page title
  • embedded video file is missing text alternative
  • embedded audio file is missing text alternative
  • table that only has TH elements in it
• Changed from positive to negative ("issue found" vs "not found"):
  • table has no scope attributes
  • table has no table headings
  • table has an empty table header
• Not changed much (from "different issue found" to "not found"):
  • table nested within table header

The changes don't change the overall result much. Barriers found is still 27% and barriers and potential barriers found has increased by one percent point to 28%.

It is not clear whether the changes from positive to negative were due to changes in aXe or due to human error.

[selfthinker]

Sorry, closing this as the PR is against the wrong branch. The equivalent PR will be #18.

[selfthinker]

Oh, I have seen how you can change it (couldn't find it the first time I looked), so will re-open and change instead.