previewer: d3js csv previewer

* Adds d3js csv previewer.

Signed-off-by: Adrian Pawel Baran <adrian.pawel.baran@cern.ch>
27: D202 No blank lines allowed *after* function docstring, found 1
52: D202 No blank lines allowed *after* function docstring, found 1
61: D400 First line should end with '.', not 'g'