* npm: upgrade to 1.2.15

* crypto: Improve performance of non-stream APIs (Fedor Indutny)

* tls: always reset this.ssl.error after handling (Fedor Indutny)

* tls: Prevent mid-stream hangs (Fedor Indutny, isaacs)

* net: improve arbitrary tcp socket support (Ben Noordhuis)

* net: handle 'finish' event only after 'connect' (Fedor Indutny)

* http: Don't hot-path end() for large buffers (isaacs)

* fs: Missing cb errors are deprecated, not a throw (isaacs)

* fs: make write/appendFileSync correctly set file mode (Raymond Feng)

* stream: Return self from readable.wrap (isaacs)

* stream: Never call decoder.end() multiple times (Gil Pedersen)

* windows: enable watching signals with process.on('SIGXYZ') (Bert Belder)

* node: revert removal of MakeCallback (Trevor Norris)

* node: Unwrap without aborting in handle fd getter (isaacs)