Fix build doc on travis, and tests on drone.

- Docs building scripts need to access examples.
- Fix travis hook for readthedocs
- Work around argh v0.25 bug
- Add .nojekyll
- Fix matplotlibrc
- Make travis trigger drone.io on success.
- relax req. on y0 and tout for integrate_sundials()
- BUG: Fix failing tests for sundials.
- Use Miniconda (3-)3.7.0.
Merge branch 'enhance_drone'