install: fix openbsd man page location

Man pages go into $PREFIX/man on OpenBSD, not $PREFIX/share/man.
doc: add Google+ French community
blog: post about streams2 feature
bench: use res.end() for chunked encoding

Use res.end() for the final chunk so we can benchmark the 'hot path' shortcut
in lib/http.js that packs the headers and the body into a single packet.
http: pack response body buffer in first tcp packet

Apply the same optimization to res.end(buf) that is applied to res.end(str).

Speeds up `node benchmark/http_simple_auto -k -c 1 -n 25000 buffer/1`
(non-chunked response body) by about 750x. That's not a typo.

Chunked responses:

  $ cat tmp/http-chunked-client.js
  // Run `node benchmark/http_simple` in another terminal.
  var http = require('http'), url = require('url');
  var options = url.parse('http://127.0.0.1:8000/buffer/1/1');
  options.agent = new http.Agent({ maxSockets: 1 });
  for (var i = 0; i < 25000; ++i) http.get(options);

Before:

  $ time out/Release/node tmp/http-chunked-client.js
  real    16m40.411s
  user    0m9.184s
  sys     0m0.604s

After:

  $ time out/Release/node tmp/http-chunked-client.js
  real    0m5.386s
  user    0m2.768s
  sys     0m0.728s

That's still a 185x speed-up.

Fixes #4415.
blog: Update blog post re streams2
blog: More streams2 wordsmithing
npm: upgrade to 1.1.70
blog: Post about v0.9.4
lint
build: allow to specify custom tags

When building custom `node` versions (e.g., floating features/fixes from
different versions) it's often useful to specify a custom tag which
easily identifies build when invoking `node -v`.

Introduce a way to specify this tag in `node_version.h` file or by
running `./configure --tag="<tag>"`. Insert it right after the patch
version (and before `-pre`, if build is not a release).
deps: upgrade libuv to 4997738
blog: Post for v0.9.5
doc: add CONTRIBUTING.md
os: change CPU time from Integer to Number

CPU time values must be Numbers, not Integers, as they can be too large
for Integers on 32 bit platforms.
doc: improve example of process.hrtime()

The example clarifies now that diff[0] * 1000000000 + diff[1] equals
the result in nanoseconds.