test: strip copyright boilerplate

Commit 3e1b1dd4 missed a few files in test/parallel, this commit
rectifies that.

Only test/parallel/test-url.js still has a copyright header.  I left
it in because the original author is neither an io.js contributor nor
a StrongLoop employee.

PR-URL: https://github.com/iojs/io.js/pull/527


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>