Log Message:
Update lang/nodejs6 to 6.12.0.

assert:
- assert.fail() can now take one or two arguments

crypto:
- add sign/verify support for RSASSA-PSS

deps:
- upgrade openssl sources to 1.0.2m
- upgrade libuv to 1.15.0

fs:
- Add support for fs.write/fs.writeSync(fd, buffer, cb) and
  fs.write/fs.writeSync(fd, buffer, offset, cb) as documented

inspector:
- enable --inspect-brk

process:
- add --redirect-warnings command line argument

src:
- allow CLI args in env with NODE_OPTIONS
- --abort-on-uncaught-exception in NODE_OPTIONS
- allow --tls-cipher-list in NODE_OPTIONS
- use SafeGetenv() for NODE_REDIRECT_WARNINGS

test:
- remove common.fail()