XDOCKER-101: Upgrade stable version to 11.2

* More progress, still not working. I have an issue with "jdbc:postgresql://replacecontainer:5432/replacedatabase" not working and generating " Caused by: java.net.UnknownHostException: xwiki-postgres-db"
* Added ascii art in Dockerfile
* Renamed containers so that we can run several xwiki images on the same machine without conflict

* Use a better name for the property (thanks to Tianon)

* Prepare the field by generifying the templates/build and docker files

 XDOCKER-10: Cannot change database name
* Add leftover that was forgotten

[Misc] Improve doc (was committed as part of "XDOCKER-13: Add an image tag for XWiki 9.0 and publish on dockerhub" on the 9.x branch)

[Misc] Fix wrong VOLUME location issue introduced when I refactored the code to depend on the tomcat image instead of on debian jesse directly...

[Misc] Apply best practices as reported by yosifkit on https://github.com/docker-library/official-images/pull/2563#issuecomment-276541490
* Removed the not needed sh files
* Allow passing parameters to catalina.sh from the docker command line
* Removed unnecessary apt upgrade + unncessary --force-yes option
* Verify sha of xwiki war to make sure the right WAR is downloaded and avoid man in the middle attacks
* Simplify the sed expression and do it in one step
* Remove unnecessary EXPOSE (done by the tomcat image)
* Install the MySQL JDBC driver using apt-get (libmysql-java package) instead of getting it directly from upstream