add tests

[dodo]

some tests for this package landed in node-xmpp. i think this deserves its own tests.

[lloydwatkin]

What tests are you referring to @dodo, would like to get them moved into node-stringprep-icu and this closed down. If it was just leakcheck.js then this has been moved to a test in the repo.

[dodo]

i meant some of the jid tests like should parse a JID with punycode.

[lloydwatkin]

ok, will look to get them migrated.