Add .editorconfig file

Editorconfig file is a cross-editor configuration system for indentation
and other stylistic settings.
Add "Goals and Priorities" list to README
Reorganize secrets and example files

- Secrets are now stored in a folder (this will come in handy as I roll
  out tinc support), as opposed to a single file.
- The included hosts file has been given an `.example` suffix, as you'll
  probably want to change it anyways.
- The `.gitignore has been updated appropriately to reflect the new
  structure.