CMS: ispy-online visualization

* Adds `invenio-previewer-ispy` dependency.  (PR #165)

Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>
templates: global unification of indentation

* Unifies indentation to two spaces everywhere (HTML, CSS, JS, Jinja).

* Replaces tabs with spaces.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>