As a Jira Admin I'd like to change the default notification email subject line

Problem Definition

Currently, the default email subject line is hardcoded 

EmailSubjectManagerImpl#DEFAULT_REQUEST_EMAIL_SUBJECT = "${issue.key} ${issue.summary}" 

Suggested Solution 

Although it is possible to change this value on a per-project basis from the customer notification settings page, it would be great to have the ability to change this default value so we don't need to update every new project they create.