Added optional parameter 'id' to JSON for BarChart
Added optional parameter 'id' to Jit BarChart, because the previous implementation was not allowing two or more same labels.
If an id is not specified, it is using key => value, where key is the label, and for two same labels it would not count the second one.
If an id is specified, it will use id => value.
Merge pull request #149 from bor0/master

Added optional parameter 'id' to JSON