Add more examples

[Shekharrajak]

These are many things we can do using Highcharts, GoogleCharts, Nyaplot, DataTables. I tried to add most of the basic examples in iruby notebook/rails/sinatra/nanoc web application in spec folder.

But there are many advance examples we can show for the highcharts, that must be added in iruby notebook spec/dummy_iruby

few are present here (for highcharts) : https://www.highcharts.com/community/charts/