add a descriptive title to delete instance view

When the delete view is displayed, the title was "Undefined Server" which is confusing. This patch will display "Delete <vmname>" similar to the migrate view.

https://drive.google.com/file/d/0B9DbsE2BbZ7uVEVwLUJnVXRBb0E/edit?usp=sharing

Signed-off-by: Tyler Baker <tyler.baker@linaro.org>