Settings and logging tweaks

- Fixing syntax highlighting in Textmate / Sublime Text.
- Test settings only added conditionally now to help when pylytics is installed in editable mode by pip.
- The table name is included in a couple more logging statements.
- library/settings.py now uses the colour output definitions from library/log.py.
- Sentry no longer used if no Sentry settings are present. 
Does this now return `None` if no DSN is configured?