Implement error handling for settings functions loading

[toonarmycaptain]

Currently an empty or malformed settings.py will cause an error. Future planned reimplementation as JSON text file will not solve this issue.
Ideally error handling will handle these cases:

• Empty settings.py file.
• Malformed/invalid python settings.py file
• Malformed or invalid data in settings.py file eg:
  • 'database': 'redis'
  • Invalid path for chart save folder.
• Check for valid schema/keys.
• Check for anything except expected single dict - protect against running unexpected code?