add more tests

[bcoe]

I've added some more tests, increasing the test coverage significantly. In the process I've nuked some dead code.

@sindresorhus could you perhaps add me as an owner to the wrap-ansi npm module, and I'll work on getting this module pulled into cliui -> yargs -> finally gulp.

reviewers: @dthree, @sindresorhus

[sindresorhus]

could you perhaps add me as an owner to the wrap-ansi npm module

Done. Use np for publishing ;)

[dthree]

👍 lgtm