Bokeh

- integrated bokeh on backend&frontend side (bbossy's changes)
- added example workbook
- started work on "simplification" layer for bokeh-scala (imho poorly documented, please give feedback here -> software design could probably be better... not 100% sure yet on which direction to take). Idea: simplify the 80% tasks/plots data analyst have to do in terms of plots/statistical analysis.
- added spark configurator workbook
This is a very good starting point I must say. We will see at usage how this should evolve (hard to come with the good abstraction level).
Maybe shall we directly integrate the tools which are rather cool (pan, zoom, export).