Add option for grid in cell plots

[bedantaguru]

• [x] for ggplot2 add optional grid argument
• [ ] for DT add option to have numeric column (instead of A, B, C --> 1, 2, 3)

[bedantaguru]

Both DT and ggplot2 has to be tuned and shiny modules have to be resynced

[bedantaguru]

Change default behaviour to gird on in ggplot2