bump the version to 0.0.18

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
fix py33 error in setup.py

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
fix foobared v 0.0.18 by using right execnet tag

Signed-off-by: Alfredo Deza <alfredo@deza.pe>