Bump release to 1.8.0 (jazzband#303)

Bump release to 1.7.0

Added:

- New `add` command (jazzband#202)
- Add lunar start time options to the `report` and `log` commands (jazzband#215)
- Aggregate reports by day (jazzband#231)
- Fish shell completion (jazzband#239)
- Add support for first day of the week configuration in reports and logs (jazzband#240)
- Python 3.7 support (jazzband#241)
- Add `start --no-gap` and `stop --at` options (jazzband#254)

Changed:

- The `edit` command now checks data consistency (jazzband#203)
- Current state saving is now improve when using Watson as a library (jazzband#214)
- Prevent calling `get_start_time_for_period` multiple times (jazzband#219)

Fixed:

- Improved support for UTF-8 with Python 2 (jazzband#211)
- Zsh completion for tags and projects with spaces in their names (jazzband#227)
- Typos in commands output (jazzband#230, jazzband#235)
- Project URL of the project in PyPI (jazzband#260)

Removed:

- Python 3.3 support (jazzband#210).

Bump release to 1.6.0

Bump release to 1.5.2

- Fix the `config` command (jazzband#158)

Bump release to 1.5.0

Tagging release 1.4.0

Bump release to 1.3.2

Bump release to 1.3.1

Update release notes