Update lang/nodejs to 6.0.0.

This release will become the new LTS later in 2016.

The following significant changes have been made since the
previous Node.js v5.0.0 release.

Buffer
- New Buffer constructors have been added #4682 and #5833.
- Existing Buffer() and SlowBuffer() constructors have been
  deprecated in docs #4682 and #5833.
- Previously deprecated Buffer APIs are removed #5048, #4594.
- Improved error handling #4514.
- The Buffer.prototype.lastIndexOf() method has been added #4846.

Cluster
- Worker emitted as first argument in 'message' event #5361.
- The worker.exitedAfterDisconnect property replaces
  worker.suicide #3743.

Console
- Calling console.timeEnd() with an unknown label now emits a
  process warning rather than throwing #5901.

Crypto
- Improved error handling #3100, #5611.
- Simplified Certificate class bindings #5382.
- Improved control over FIPS mode #5181.
- pbkdf2 digest overloading is deprecated #4047.

Dependencies
- Reintroduce shared c-ares build support #5775.
- V8 updated to 5.0.71.35 #6372.

DNS
- Add dns.resolvePtr() API to query plain DNS PTR records #4921.

Domains
- Clear stack when no error handler #4659.

Events
- The EventEmitter.prototype._events object no longer inherits
  from Object.prototype #6092.
- The EventEmitter.prototype.prependListener() and
  EventEmitter.prototype.prependOnceListener() methods have been
  added #6032.

File System
- The fs.realpath() and fs.realpathSync() methods have been
  updated to use a more efficient libuv-based implementation. This
  change includes the removal of the cache argument and the method
  can throw new errors #3594.
- FS apis can now accept and return paths as Buffers #5616.
- Error handling and type checking improvements #5616, #5590,
  #4518, #3917.
- fs.read's string interface is deprecated #4525.

HTTP
- 'clientError' can now be used to return custom errors from an
  HTTP server #4557.


(fhajny)