New widget [form to change config], solved the UI glitches
 * notebook.front.widgets.Spark → can replace `reset` when the notebook can be changed for testing purpose
 * `reset` is kept in case the configuration is known and we want to keep it in the widget (→ might change)
 * some glitches were introduced by including new JQuery UI + Bootstrap (cursor, header, icons and so on) →  fixed
 * the Streaming example is now showing the values in a Rickshaw timeseries graph rather than text
Merge pull request #10 from andypetrella/spark-conf-form

New widget [form to change config], solved the UI glitches