src: add node_isolates

Few primitives weren't being passed node_isolate. Adding them for
consistency.
fs_event: use cached Persistent syms instead

Instead of String::New every time, use a Persistent sym. This can be
accomplished in two ways:

1) Local<String> str = *persistent_str_sym;

2) Handle<String> str = persistent_str_sym;

I've chosen to use the latter method for simplicity's sake.

Other small changes include creating syms on Initialize and removing
unnecessary Local casting on return values.
Merge remote-tracking branch 'ry/v0.10' into master

Conflicts:
	AUTHORS
	ChangeLog
	deps/uv/ChangeLog
	deps/uv/config-unix.mk
	deps/uv/src/unix/stream.c
	deps/uv/src/version.c
	deps/uv/uv.gyp
	src/node.cc
	src/node_buffer.cc
	src/node_crypto.cc
	src/node_version.h
	src/stream_wrap.cc
	src/stream_wrap.h
module: use path.sep instead of a custom solution

Instead of using a custom solution we can use path.sep in
Module._nodeModulePaths
net: readd DTRACE_NET_SOCKET_(READ|WRITE) probes
dtrace: unify dtrace and systemtap interfaces
systemtap: add tapset for node user probes

This makes systemtap tracing prettier, you can do things like `stap -e
'probe node_http_server_request { println(probestr); }'`