- Rename script to correspond with repository name
- Bring in to compliance with `shellcheck`
- Add some output explaining what script is doing
- Add new options:
- `--no-systemd` will not perform any Systemd steps
- `--no-enable` will not enable the Systemd service
- `--no-start` will not start the Systemd service
- `--no-binary` will not install the Syncthing binary
