Update CI scripts and fix linting errors

[leouieda]

Pylint 2.4.2 generates some new error reports, mostly due to imports not
being at the top.
Update CI scripts to 1.2.0 to fix failing TravisCI builds.
Take control of the conda path on Mac Azure builds to avoid conda
errors.

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to the docstring, gallery, and/or tutorials.