Enhance mail notification

The current email notification works when cube build success or failure, will send notification mail to "notification list" and admin DL (defined in kylin.properties).

When we enable streaming building feature, this mechanism brings spam:
for instance, every 5 minutes will got one mail about small merge job success for one data model. Suppose there are 20 data model in system will bring huge spam mails.

Enhancement after discussion:
1. Add one option with "notification list" to enable "on success" and "on failure" options
2. Cube admin could set these option value
3. Job engine will call mail service based on these settings
4. Always send failure mail notification to admin/ops DL
5. Once "on success" option be selected, mail also will cc to admin/ops DL