try adding circle config (#1)

* adding automated tests to run on Circle with selenium, still need to add screenshots
Signed-off-by: Vanessa Sochat <vsochat@stanford.edu>

Try taking screenshot (#2)

Adding screenshots (working) back in to tests, ready to PR to upstream
Signed-off-by: Vanessa Sochat <vsochat@stanford.edu>

Don't include driver binaries.

Take screenshot of only viewer element.

Don't remove Travis config, at least for now.

Run Black on tests script.

Fix automated tests for Firefox and some formatting changes.

Update test documentation.

This reverts commits 2d0230dd4e1ae77a1d7dd8705fedf0f5f4c40156,
9e23ee0b5708bb96552d15571ec966f604a43301,
e996faa86c9dcc4c3e4a859cbb75567d4e3ace91,
and d204ac06d5.

Try to replace Sauce Labs, so CI works for pull requests (#774).

Based on configuration at 60c73499fc/README.md.