Require user to enter Namespace+Repository name when deleting.

Currently, deleting a repository does not mention the repository name or its namespace. This could be dangerous in certain situation.

It would be useful to follow the user-experience practice of displaying the repository which is about to be deleted and require the User to type in the name as well.

Example message which could probably be articulated better:
"If you are sure you want to delete kmullins/quay, type kmullins/quay below"