2015-03-20 io.js v1.6.1 Release

Notable Changes:

* path: New type-checking on path.resolve()
  <https://github.com/iojs/io.js/pull/1153> uncovered some edge-cases
  being relied upon in the wild, most notably path.dirname(undefined).
  Type-checking has been loosened for path.dirname(), path.basename(),
  and path.extname(), (Colin Ihrig)
  <https://github.com/iojs/io.js/pull/1216>.
* querystring: Internal optimizations in querystring.parse() and
  querystring.stringify() <https://github.com/iojs/io.js/pull/847>
  prevented Number literals from being properly converted via
  querystring.escape() <https://github.com/iojs/io.js/pull/1208>,
  exposing a blind-spot in the test suite. The bug and the tests have
  now been fixed (Jeremiah Senkpiel)
  <https://github.com/iojs/io.js/pull/1213>.