Improved JSON serialization.

I tried a few things for better serialization:
- Drop JSON and switch to YAML.
  But the pyyaml project has not been updated since
  2011. I don't want to use a dead horse. Maybe we
  w  ill get a few problems in future...

- Drop JSON and switch to pickle or shelve. I don't
  like them because they can execute arbitrary python
  code from untrusted sources. You just have to edit
  the noterc file...

- Finally I added a JSONDecoder class and adjusted some
  Note methods. It's better I think.

refs #285.

Signed-off-by: Stefan Tatschner <stefan@sevenbyte.org>
Added a Changelog entry.

Signed-off-by: Stefan Tatschner <stefan@sevenbyte.org>
Renamed versions.json to revisions.json.

Signed-off-by: Stefan Tatschner <stefan@sevenbyte.org>
Improved data model.

It is very easy:
- Most recent revisions are in data.json.
- Deleted notes with a deletion date are in trash.json.
- Outdated revisions are in revisions.json

Fixes #285, #276.

Signed-off-by: Stefan Tatschner <stefan@sevenbyte.org>
Some last minute changes, bumped version number.

Signed-off-by: Stefan Tatschner <stefan@sevenbyte.org>
Merge branch 'release/0.1'
Merge tag '0.1' into develop

pynote 0.1