Tattler

- Fix regression from 1.2.0 preventing loading of templates.
- Fix regression from 1.2.0 where priority of HTML content causing some clients to favor plain text display.
- New demo notification packed with useful tips and reusable style/elements for your own templates.
- Support hostnames in TATTLER_SMTP_ADDRESS envvar.

- Ship with Jinja as default template engine to simplify installation and docs.
- Context plug-ins now inherit ContextPlugin class.
- Renamed demo notification to `demoscope`/`demoevent` (from `sample`).
- Improved documentation, now broken down into sections.
- Added ready-to-use examples for plug-ins that query SQL database.

- Fix built-in demo failing to build the sample SMS template.
- Some rearrangement of the codebase to keep as much of tattler-enterprise as possible in tattler-community too.

- Move SMS templates from event/sms to own subfolder event/sms/body.
- Clearly annotate features specific to enterprise edition in docs.

- Initial release