Refactor frontend address spec

This spec has failing on the CI for a while. The reason might be that it
used capybara `find` to check the visibility of elements and that method
does not wait until the element become either visible or not visible so
depending on the page load time the spec may get confusing results.

`has_selector?` is probably a better choice since we can specify
explicitly the `visible` option

Just an attempt to fix the failing spec on the CI. Did some research and found this http://stackoverflow.com/a/8818598/831036 which I think makes sense. The spec might take a little bit longer to run but at least it brings better results.

It this gets merged in please cherry-pick to 2-0-stable.