Instead of looking for a "secret" field hmac is used. Therefore the
raw payload is hashed with all secrets consecutively in order to
validate its content. If the content is certified the established
behaviour is pursued..
To create a minimalistic parser, nom is used to identify and replace
parameters given in the command field.
For clarity the `action` field for hooks was renamed to `command`.
All dependencies were updated.
An example configuration file `config.yml` is added to show the
configuration options. Following locations are checked:
- `/etc/webhookey/config.yml`
- `<config_dir>/webhookey/config.yml`
- `./config.yml`
Whereas `<config_dir>` is depending on the platform:
- Linux: `$XDG_CONFIG_HOME` or `$HOME/.config`
- macOS: `$HOME/Library/Application Support`
- Windows: `{FOLDERID_RoamingAppData}`
Each hook's action is executed if all of the specified filters match.
