The starting scripts now `exec` the main service instead of starting
it as a subprocess. Also in line with docker-entrypoint recommendations.

the former code showed each character of the preview thumbnail urls in an image tag, which filled up the page without sense

Signed-off-by: fenn-cs <fenn25.fn@gmail.com>

In the bbb-lti applicaation, add a way to configure the parameters used for generating the meetingID (#6714)

* Can now configure parameters used to generate meeting_id

* Add back deleted config stuff

* Fix documentation typo

* Fix bad indentation

* Change function name

* Added support for HMAC SHA256 encryption

* Added back accidentally deleted line

* Moved oauth library to seperate repository

* Fixed weird indentation in ToolController.groovy

* Fix listing multiple playbacks
* Fix localization
* Consider X-Forwarded-Proto header to determine which endpoint to use
* Allow custom context different than /lti
* Add pt_BR strings

Suggested solution for https://groups.google.com/forum/#!topic/bigbluebutton-dev/2q43YPSAu0o