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.
deps: update v8 to 3.15.11
bindings: update to new v8 apis

GetPointerFromInternalField() is deprecated now, we should use
GetAlignedPointerFromInternalField().
test: make tests work with newer v8
v8: remove optimization switches

Remove compiler switches from $(TOPLEVEL)/deps/v8/build/common.gypi,
we set them globally in $(TOPLEVEL)/common.gypi.

Commit 7b4d95a introduced the switches again, resulting in V8 getting
built without any optimizations.

This commit is essentially a rehash of commit 4b8629d.
Merge remote-tracking branch 'origin/v0.8'