Implement the URL alias screen
cf https://doc.ez.no/display/PR/Content+view+subtabs#Contentviewsubtabs-URLstab
Scenario 1: viewing urls
Given that I am on a content view of an object
When I click on the "URL" subtab
Then I see a table with the summary of all URLs existing to access the content with a distinction between system URL and URL alias

Scenario 2: creating url alias
Given that I am on a content view of an object on the url subtab
When I click on the "add an url alias"
Then I see a form where I can add a new url alias to a content

Scenario 3: deleting url alias
Given that I am on a content view of an object on the url subtab
When I select an url alias and click on delete
Then the url alias is removed