add some docs regarding to Emitter
Merge pull request #464 from luvit/songgao/emitter_doc

add some docs regarding to Emitter
bump libuv to v0.10.27

Mostly for this fix:
  https://github.com/joyent/libuv/pull/1217
Merge pull request #465 from luvit/fixes/libuv_bump

bump libuv to v0.10.27