[WIP] Selenium tests

[dougthor42]

This adds selenium integration tests.

This helps make sure that #162 doesn't happen again.

Still to do:

• More tests
• update changelog
• additional web browsers?
• Safely skip the selenium tests if selenium or the webdriver or the browser itself is not installed.

[dougthor42]

Note: I verified that removing f093aba (#169) results in the selenium tests failing. So these correctly check that the #162 has been fixed.