Generate error message if report writing fails

[whereswaldon]

Steps:

• [x] Write test that ensures that the reporter throws an exception when it fails (by programmatically changing permissions)
• [x] Modify reporter to throw exceptions instead of swallowing them
• [ ] Add tests to Notifier for error surfacing functionality
• [ ] Add methods to Notifier to send error messages
• [x] Modify Scatt to catch exceptions from the reporter and give the user an error message if there is one

[whereswaldon]

Turns out the simplest thing is to not write extra Notifier tests and methods, but to reuse the existing ones.