Make recovery process require email be explicitly enabled

When JIRA starts up the options in the bin/setenv script allow email processing. This is a problem with restored data in a test instance if you forget to disable it - emails destined for a production instance of JIRA get processed by the test instance.
I suggest that email be disabled after a restore from XML action until explicitly enabled. This could be as simple as making the "Successful Restore" screen contain text about this and contain a link to the appropriate Admin page. For database restores, it's still a problem. This could have saved a number of my JIRA clients from being very puzzled when testing their backup JIRA "breaks" their production JIRA.