C++ code node v0.8 compatibility
Node v0.8 streams compability

Mostly, this is achieved by using readable-stream;
The fs streams used for testing use a mapping from the
'close' event to the 'finish' event.
Include node v0.8 in travis.yml
Use the close -> finish event forwarding only for node v0.8
Merge branch 'optional-async'
Version increase to 0.2.3 and indicate node v0.8 support