Add support for Pdf file generation

Add support for pdf file generation.
The PDF file that will be generated will contain just a simple table (or more than one, when used with Databooks).

In order to enable pdf generation, I had to rely on the reportlab package. I see you included external packages in the project itself instead of using pip for that matter. I'm not sure I did the right thing simply adding reportlab to project requirements, please let me know.