Squashed 'json/' changes from 2782d7c29..f82764080

f82764080 Merge pull request #579 from json-schema-org/sanity-check-strengthening
e5d5e0a2a Also prevent 'tests that' from descriptions.
eaf06b1e8 Remove the last few 'shoulds' from items descriptions.
b7da24fba Kill more shoulds from ECMA and ref tests.
85899fdf4 More description cleanup for Bengali non-ASCII tests.
b84b900f3 Remove 'should' from a format test which anyhow needed a clearer description.
721397c1f Prevent tests from using 'should' in sanity check.
68f380c6f Fix the last non-unique case descriptions.
6383ef638 Remove mistakenly duplicated anyOf tests in draft{4,6,7}.
a5b459fa0 Make sure bignum cases have unique descriptions.
b82b18cdf Assert case descriptions are also unique in sanity checks.
d3d082219 Also check case description length in sanity checks.
5e7804c52 Use subtests when running sanity checks.
8ade92340 Fix two last clashing $ids in draft-next too.

git-subtree-dir: json
git-subtree-split: f8276408005489aa134ec857f5fd3f0fb3ec5954