Security group create/delete confirmation fixes for GUI-1098 and GUI-1179

- Remove errant template.format() call in delete security group view handler to avoid 500 error
- Add newly-created security group name to confirmation message to fix GUI-1098
- Minor PEP8 cleanup.

https://eucalyptus.atlassian.net/browse/GUI-1098
https://eucalyptus.atlassian.net/browse/GUI-1179