Tests that require javascript (capybara-webkit) from lxc

[daronco]

There are a few tests in the application that require javascript to run properly. For those, capybara-webkit can be used. There is even a tag called :with_js that can be used to enable capybara-webkit to just a single block of tests.

However, these tests do not work if they are running from a virtual machine without a display, such as when running the tests from lxc. There should be a way to make them work in such contexts. If not, they could be automatically disabled when there's no display available and enabled when there is (also assuming the CI can run them, otherwise they will never be executed).