Add parent and children commands.

Plus supporting methods.

Also move script to a console entry point.

Towards a fix of #17.
Pep8 adjustments.

Also removal of old tool.py.
Add travis config.

Update chane log.

sudo: false

Add click to setup.
Make tests more portable.

Use integer division in parent().
Add Travis badge.
Merge pull request #20 from mapbox/issue17

Issue17