h-card validation tests

[fluffy-critter]

It'd be helpful if the webmention.rocks test suite provided some h-card examples to test various edge cases. For example, my h-card contains:

    <a class="u-email" href="mailto:fluffy%40beesbuzz%2ebiz">fluffy at beesbuzz dot biz</a>

which provides a valid email address to user-agents which URL-decode correctly (such as web browsers), but prevents naively-written spam harvesters from picking the address up. This email link has ended up tripping up a couple of webmention receivers, though.

Relatedly, it should also test to make sure that webmentions get received properly even if an optional attribute is malformed; even if my email link were invalid (e.g. mailto: fluffy AT beesbuzz DOT biz), that should not cause receiving the webmention to fail.