Update to XWiki 8.4.1 with many improvements

[ldubost]

Update Dockerfile with:

• Support for XWiki 8.4.1 and Java 8
• Added libreoffice server
• Added xinit to manage xwiki instance
• Added webapps/ROOT/index.html to redirect to XWiki page from root URL
• Persistence handled in a data container
• Change distributionId to xwiki-enterprise-docker to identify installs using this Dockerfile
• Added quickRun.sh for one click build and run

[vmassol]

@ldubost FYI I'm currently porting your changes to the VERSION2 branch which will become the MASTER soon.

[vmassol]

Support for XWiki 8.4.1 and Java 8

Already on VERSION2 branch

Persistence handled in a data container

Already on VERSION2 branch

Change distributionId to xwiki-enterprise-docker to identify installs using this Dockerfile

Merged in VERSION2 branch

[vmassol]

Closing since the changes have been incorporated already (and xinit cannot be since it won't work with docker philosophy). Thanks!