Update node.js to 0.8.18

2013.01.18, Version 0.8.18 (Stable)
* npm: Upgrade to v1.2.2
* dns: make error message match errno (Dan Milon)
* tls: follow RFC6125 more stricly (Fedor Indutny)
* buffer: reject negative SlowBuffer offsets (Ben Noordhuis)
* install: add simplejson fallback (Chris Dent)
* http: fix "Cannot call method 'emit' of null" (Ben Noordhuis)

2013.01.09, Version 0.8.17 (Stable), c50c33e9397d7a0a8717e8ce7530572907c054ad
* npm: Upgrade to v1.2.0
  - peerDependencies (Domenic Denicola)
  - node-gyp v0.8.2 (Nathan Rajlich)
  - Faster installs from github user/project shorthands (Nathan Zadoks)
* typed arrays: fix 32 bit size/index overflow (Ben Noordhuis)
* http: Improve performance of single-packet responses (Ben Noordhuis)
* install: fix openbsd man page location (Ben Noordhuis)
* http: bubble up parser errors to ClientRequest (Brian White)