Fix CircleCI System Tests

CircleCI is currently failing builds. Here's the relevant console output.

Teaspoon running default suite at http://127.0.0.1:45874/teaspoon/default
bundler: failed to load command: teaspoon (/home/circleci/repo/vendor/bundle/ruby/2.4.0/bin/teaspoon)
Selenium::WebDriver::Error::SessionNotCreatedError: session not created: This version of ChromeDriver only supports Chrome version 74

It's broken for 2 reasons.

1) Google updated their chromedriver API and chromedriver-helper has not been updated yet. I've switched to the more flexible and actively maintained webdrivers gem for that reason.

2) CircleCI, Chrome, or chromedriver isn't playing nice with the disable-dev-shm-usage driver argument that was previously necessary for TravisCI. So, I removed that argument. I also removed no-sandbox since that is enabled by default on most containers and updated the capybara gem for good measure.

Type of Pull Request

Based on the [contributor's guide][contrib-guide], this PR is of type:

[x] Development (feature-branch -> dev)
[ ] Hotfix (hotfix-branch -> master)
[ ] Release (release-branch -> master)
[ ] Other

Requestor Checklist

Requestor: Put an x in all that apply. You can check boxes after the PR has been made.

Reviewer: If you see an item that is not checked that you believe should be, comment on that as part of your review.

[ ] Code Quality: I have written tests to ensure that my changes work and handle edge cases
[ ] Code Quality: I have documented my changes thoroughly (using [JSDoc][jsdoc] in Javascript)
[ ] Process: I have linked relevant issues, [marking issues][gh-marking-issues] that this PR resolves
[x] Process: I have requested at least as many reviews required for this PR type (2 or 3)
[x] Process: I have added this PR to the relevant quarterly milestone
[x] Process: I have tested this PR locally and verified it does what it should

How This Has Been Tested

On my Ubuntu 18 virtual box, I fresh installed Chrome using commands from the CircleCI script, removed chromedriver, and then ran teaspoon and rails test:system. The correct chromedriver was fetched and all tests passed fine.

vkoves / carpe