Signal-cli

* updated signal-cli to version 0.8.0
* added experimental support for native images
* documentation improvements (thanks to Colgaton)

* added API endpoints to block/join/quit Signal Groups

* Improved usability when connecting via docker exec to the running container
* Updated signal-cli to version 0.7.4
* Added endpoint to list + trust identities
* Fixed parsing issues in groups endpoint + added missing information to the endpoint
* Added endpoints to list/change configurations

* Improved usability when connecting via `docker exec` to the running container
* updated signal-cli to version 0.7.4
* added endpoint to list + trust identities
* fixed parsing issues in groups endpoint + added missing information to the endpoint
* added endpoints to list/change configurations

This is a pre-release and only available on dockerhub with the dev tag. If you want to give it a try, pull the dev version with `docker pull bbernhard/signal-cli-rest-api:latest-dev`

* updated `signal-cli` to version 0.7.2
* added health endpoint - used by the docker daemon to perform health checks (see https://github.com/bbernhard/signal-cli-rest-api/issues/63)
* added endpoint to the update profile
* added endpoint to query attachments (see https://github.com/bbernhard/signal-cli-rest-api/issues/52)
* fixed bug that prevented to create a new Signal group (see https://github.com/bbernhard/signal-cli-rest-api/issues/54)
* fixed some markdown formatting issues (thanks to x-jokay)
* added docker container health checks (thanks to x-jokay)
* change base docker image to reduce docker image size (thanks to x-jokay)
* added possibility to specify captcha in register endpoint (see 19)

* fix "setpriv: libcap-ng is too old for 'all' caps" error (see 46)