Gephi Exporting Statistics to CSV

[marcrabat]

issue #1980
We managed to do the pull request correctly since we have sent you the code as a zip file.

In order to minimize the changes in the code, we have done the following:

• Implementation of a static class CSVCreator inside StatisticPlugin that generates the csv data receiving the object XYSeries as a parameter.
• For each class implementing getReport() we have added the csv string that appends the csv data created with CSVCreator after the tag, which we have thinked it was the more consistent separator mark.
• Finally we have added in UIComponents the export button as well as its icon which retrieves the the data that comes SIMPLEHTMLReport in order to save the file in the system.

Sorry for the inconvenients.

[eduramiba]

Thanks, closing #1980 then and we will review this one.

[Pepe-Marquez]

#1935 I guess this is related to this PR.