2015-04-20 io.js v1.8.1 Release

Notable Changes:

* build: revert vcbuild.bat changes
* changes inherited from v1.8.0:
  * build: Support for building io.js as a static
    library (Marat Abdullin) #1341
  * npm: Upgrade npm to 2.8.3. (Forrest L Norvell) #1448
  * deps: upgrade openssl to 1.0.2a (Shigeki Ohtsu) #1389
  * src: allow multiple arguments to be passed to
    process.nextTick (Trevor Norris) #1077
  * module: the interaction of require('.') with NODE_PATH has been
    restored and deprecated. This functionality will be removed at
    a later point. (Roman Reiss) #1363