Fix problem with doc deployment

[dwhswenson]

Sometime around/after #883, our docs stopped uploading to the website. This fixes that problem. By developing this in the docs_deploy branch, the new docs have already been uploaded. Merging this in will ensure that docs continue to upload.

This also bumps our copyright date to include 2020.

Will merge in 24 hours if no discussion.

[dwhswenson]

This also includes fixes for a couple other CI-related things:

• coveralls wasn't getting all our information, because:

  1. python-coveralls isn't compatible with coverage 5.0 (see Breaks with coverage 5.0 z4r/python-coveralls#73); remedy was to switch to the coveralls package instead (I feel like I've switched back and forth between these two several times).
  2. Use Autorelease for version/release management #883 had accidentally removed the COVERALLS_PARALLEL environment variable from the .travis.yml; remedy is to add it back.

• pytest 5.3.4 (published while I was working on this PR) is not compatible with nose's @raises decorator (see 5.3.4 causing internal errors pytest-dev/pytest#6517); remedy is to pin pytest!=5.3.4.

Still planning to merge late this evening if no discussion.