installation: location of demo_table_jui.css

* Fixes location of demo_table_jui.css by explicitly referencing last
  git tag that contained the file.

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
Merge pull request #1954 from kaplun/fix-install-demo_table_jui

installation: location of demo_table_jui.css