URL parse error when the name of a project ends in `.atom`

When a project name ends in .atom there is a URL generation error that causes the dashboard and the profile page of a user to give a 500 error.

This is the exact error being outputted.

ActionController::UrlGenerationError - No route matches {:action=>"show", :controller=>"projects", :id=>#<Project id: 117536, name: "a.atom", path: "a.atom", description: "", [...] missing required keys: [:id]:

Renaming the project to a-atom, in this case, solved the problem.

@yorickpeterse I believe you worked on the atom feeds recently. Can you have a look, please?

/cc @rspeicher @JobV