Nekrosis

- Linux changes/improvements:
- Detect if `cron` is available before presenting it as an option.
- Detect if distribution is `systemd`-based before presenting it as an option.
- Avoid printing cronjob status to STDOUT.
- macOS changes/improvements:
- Detect if `cron` is available before presenting it as an option.
- Expanded Electron persistence method to support root persistence.
- LaunchDaemon - Electron
- Windows changes/improvements:
- Add `Shortcut (Current User)` as recommended option
- General changes/improvements:
- Resolve logging error with subprocess failures.
- Set project to `Production/Stable` status.

- setup.py: Resolve local file references when publishing to PyPI
- ex. images and file URLs
- Linux changes/improvements:
- Add `Systemd`-based persistence method.
- `SystemdService` (requires root)

- Windows changes/improvements:
- Switch to admin detection via UAC for privilege status.
- Add `Startup folder`-based persistence methods.
- `Startup Folder (Current User)` (default)
- `Startup Folder (All Users)` (requires admin)
- Windows: Add `Registry`-based persistence method.
- `RUNKEY` (requires admin)
- Windows: Add `Shortcut`-based persistence method.
- `Shortcut (Current User)`
- macOS/Linux changes/improvements:
- Add `Cron`-based persistence method.
- `Cron (Current User)`
- `Cron (Root)` (requires root)
- General changes/improvements:
- Add support for specifying persistence method as index in addition to name.
- Add support for providing payload as a URL.
- Rename Application Entry Point to `nekrosis.py` (from `nekrosis_entry.py`).
- Does not affect library usage.
- New arguments:
- Add new `-n/--nuke` option to delete payload and Nekrosis on exit.
- Add new `-s/--silent` option to suppress STDOUT/STDERR output.
- Add new `-e/--export` option for exporting supported persistence methods to standardized formats.
- Supported formats:
- `JSON`
- `XML`
- `PLIST`
- Publish new project metadata:
- `__title__`
- `__description__`
- `__url__`
- `__status__`
- `__author_email__`

- Initial release.