Reference Rubocop config from Hound config

rather than the inheriting the other way around (see b17d3faf).

[ci config]

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Tell Hound to run JavaScript style checks (JSHint)

[ci skip]

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #2171 from opf/feature/houndci-js-support

Enable JavaScript style checking with Hound