- Fix to make parse_url support file paths or URLs
Remove local imports from trigger/utils/__init__.py
- Update global settings and sample trigger_settings.py to use NETDEVICES_SOURCE, remove NETDEVICES_FORMAT, assign NETDEVICES_FILE to NETDEVICES_SOURCE
- Remove prints from Rancid and CSV loaders
- Don't pre-build loader objects because they are only called once at startup
+ Cleanup in netdevices

  - Remove SUPPORTED_FORMATS
  - Remove deprecated _parse_* functions
  - Remove parser imports
  - Update _munge_source_data with new arg signature
  - Update _populate and NetDevices._actual constructor w/ new args
  - Replace NETDEVICES_FILE with NETDEVICES_SOURCE