2016-06-23 Version 0.12.15 (Maintenance) Release

This is a security release. All Node.js users should consult the security
release summary at
https://nodejs.org/en/blog/vulnerability/june-2016-security-releases/ for
details on patched vulnerabilities.

Notable changes:

* libuv: (CVE-2014-9748) Fixes a bug in the read/write locks implementation for
  Windows XP and Windows 2003 that can lead to undefined and potentially unsafe
  behaviour. More information can be found at
  https://github.com/libuv/libuv/issues/515 or at
  https://nodejs.org/en/blog/vulnerability/june-2016-security-releases/.
* V8: (CVE-2016-1669) Fixes a potential Buffer overflow vulnerability
  discovered in V8, more details can be found in the CVE at
  https://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1669 or at
  https://nodejs.org/en/blog/vulnerability/june-2016-security-releases/.

PR-URL: https://github.com/nodejs/node-private/pull/53