Create Jenkins Build to update WoN ontology pages on github pages branch

[quasarchimaere]

we should add a build job, that generates and publishes the WoN ontology files automatically to the github-pages branch.

Related to https://github.com/researchstudio-sat/webofneeds/pull/2924 (see this pr for a how to)

[fkleedorfer]

This is trickier than it may sound:

• gh-pages is a different branch of the same project, it's not evident how to copy into a branch currently not checked out
• for the build, we would need the widoco jar availble in the build environment. I think we would have to do something similar to @seralf here: https://github.com/dgarijo/Widoco/issues/301
• in addition to that, the current doc build is done by a bash script. I'm sure it's mavenizable but I am not sure how to make that robust and portable across platforms.

[quasarchimaere]

well i assume we can execute bash scripts after a checkout in jenkins, and i did not assume this was easy to do, if its really really reaallly hard we can also drop it and create some form of markdown how to instead (in a way that we wont forget when to update an ontology and how it is done)