Fix CI builds

[aitbw]

This PR fixes the failing CI builds by adding selenium-webdriver as a development dependency (for CircleCI), and specifying DB services / enabling chromedriver (for TravisCI)

It also removes poltergeist as it's not being used anymore.

[jacobherrington]

🎉 Thanks @aitbw!

[spaghetticode]

@aitbw thank you for helping 👍

[spaghetticode]

@aitbw as Travis is still in use, I think it would be better to fix that build as well before merging the PR. Would you please add a commit for that? I think that these changes in .travis.yml would do:

services:
  - postgresql
  - mysql

thank you! 🙏

[aitbw]

Done @spaghetticode! Thanks for the heads-up 😸

[kennyadsl]

I think we can disable Travis at all at this point, WDYT?

[spaghetticode]

@kennyadsl I agree, especially since it's still failing.

[aitbw]

@kennyadsl, I don't have any problems with it. Let me know if you'd like to submit a PR to remove Travis 🙌