WIP: ci, cd, environment and security improvements

[CameronTStark]

• Closes TST: Move Continuous Deployment to Azure, depricate Travis #950
• I am familiar with the contributing guidelines
• Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels and Milestone are assigned to the Pull Request and linked Issue.

This enables PyPI deployment via Azure Pipelines (AP) with the intention of deprecating Travis. It also adds conda py35-min testing not present in AP but in Travis.

It also implements the a better more secure way of setting environment variables used to set up tests.

Please let me know if I'm missing anything from Travis that would be missed if it was removed.

Currently the following steps need to be implemented before this will be finished:

• use the PyPI key instead of just the test.pypi.org key
• remove the .travis.yml file

[wholmgren]

now using github actions for deployment. thanks @CameronTStark for getting us started on this!