2015-03-19 io.js v1.6.0 Release

Notable Changes:

* node: a new -r or --require command-line option can be used to
  pre-load modules at start-up (Ali Ijaz Sheikh)
* querystring: parse() and stringify() are now faster (Brian White)
* http: the http.ClientRequest#flush() method has been deprecated and
  replaced with http.ClientRequest#flushHeaders() to match the same
  change now in Node.js v0.12 as per
  https://github.com/joyent/node/pull/9048 (Yosuke Furukawa)
* net: allow server.listen() to accept a String option for port, e.g.
  { port: "1234" }, to match the same option being accepted in
  net.connect() as of https://github.com/joyent/node/pull/9268 (Ben
  Noordhuis)
* tls: further work on the reported memory leak although there appears
  to be a minor leak remaining for the use-case in question, track
  progress at https://github.com/iojs/io.js/issues/1075.
* v8: backport a fix for an integer overflow when --max_old_space_size
  values above 4096 are used (Ben Noordhuis)
* platforms: the io.js CI system now reports passes on FreeBSD and
  SmartOS (_Solaris_).
* npm: upgrade npm to 2.7.1. See the npm CHANGELOG.md for details.
  https://github.com/npm/npm/blob/master/CHANGELOG.md#v271-2015-03-05