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

 * FIxed missing modification from past commit

[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)

http://jira.xwiki.org/browse/XDOCKER-11

[Misc] Fix typo in docker-entrypoint.sh that prevented using a custom mysql user name + Removed unnecessary env variable at runtime

[Misc] Go back to the previous setup which was better and I've found a way to make DockerHub happy with it.

[Misc] Since we may want to generate different images of xwiki in the future (with different dbs, different servlet containers, etc), move all current data into a xwiki-mysql-tomcat directory.

[Misc] Improved README + give a name to the xwiki-data volume + add LICENSE + improved .gitignore file