2017-03-21, Version 4.8.1 'Argon' (LTS)

Notable Changes:

* buffer:
  - The performance of `.toJSON()` is now up to 2859% faster on average
    (Brian White) nodejs#10895

* IPC:
  - Batched writes have been enabled for process IPC on platforms that
    support Unix Domain Sockets. (Alexey Orlenko)
    nodejs#10677
  - Performance gains may be up to 40% for some workloads.

* http:
  - Control characters are now always rejected when using
    `http.request()`. (Ben Noordhuis)
    nodejs#8923

* node:
  - Heap statistics now support values larger than 4GB. (Ben Noordhuis)
    nodejs#10186