Merge branch 'release/0.1.5' into develop
fix ci failure under python 2.x
make import follow pep8
Merge pull request #3 from acmerfight/develop

make import follow pep8
make exception follow pep8
Merge pull request #4 from acmerfight/develop

make exception follow pep8
tests ensure parent logic is executed only once
Fix python bug for multiprocessing.util._exit_function

Conflicts:
	tests/test_caoe.py
depends on python-prctl, which is more active
bump version to 0.1.6
Merge branch 'release/0.1.6'
Merge branch 'release/0.1.6' into develop
drop support for py2.6 and update travis.yaml
use pytest instead of nose, and use tox for test runner
bump version to 0.1.7
Merge branch 'release/0.1.7'