Merge remote-tracking branch 'upstream/v0.10'

Conflicts:
	deps/v8/src/preparser.cc
	deps/v8/src/win32-math.h
	doc/api/http.markdown
	src/node_buffer.h
	src/node_crypto.cc
	src/node_file.cc
	src/node_http_parser.cc
test: fix test-http-pipeline-flood

The number of connections achieved by the test can vary by platform
and by machine. Lowering the acceptance threshold so that the
test passes on Windows.
dns: verify argument is valid function in resolve

Don't use argument as callback if it's not a valid callback function.
Throw a valid exception instead explaining the issue.

Adds to #7070 ("DNS — Throw meaningful error(s)").
dns: validate arguments in resolver

Mitigate C++-land assertion error, add test accordingly.

Fix #7070
process: allow changing `exitCode` in `on('exit')`

fix #7081
crypto: allow custom generator for DiffieHellman