doc: mention callback for http res/req write & end

Add documentation for the callback parameter of http.ClientRequest's and
http.ServerResponse's write and end methods.
doc: fix grammar and wording in tls and timers

In `tls.markdown`, there was a misuse of 'a' which has been replaced
with 'an'.

In `timers.markdown`...
  line 31: misuse of 'a', replaced with 'an'
  line 59: unclear wording, haywire 'a', added new comma
build: do not generate support for libuv's probes

Dtrace probes were removed from libuv recently, but their usage by node
was not completely removed, causing build breaks on SmartOS.

Even though the build is working on other platforms, these probes are
not fired by libuv anymore, so there's no point in using them on these
platforms too.

Reviewed-by: Trevor Norris <trev.norris@gmail.com>
deps: update libuv to 1.0.2

PR-URL: https://github.com/joyent/node/pull/8847
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
test: mark more tests as flaky

Marking these two tests as flaky, since they have been failing
intermittenly in recent builds:
test-debug-signal-cluster
test-cluster-basic
Merge branch 'v0.12' of github.com:/andrewlow/node into v0.12-ppc