Problem with the Pie Chart generator operator

[flopezag]

Currently the invocation of the operator activate firstly the numberSerieCallback and calculate the options value in the build_pie_chart() function and then activate the labelSerieCallback and call again the method build_pie_chart() calculating again the value of the options variable.

The result is that the final data published by the operator only take care about the data provided in "label-serie" data.