Better Plotly compatibility

[smouksassi]

Opening here to keep track of it https://github.com/smouksassi/ggplotwithyourdata/issues/19 https://github.com/ropensci/plotly/issues/1139

We need to think of a better way to handle the use of aes(...= NULL ) as it is not ggplotly compatible.

[smouksassi]

the aes (group=NULL) is there to handle the fact that ggplot do some automating "grouping" under the hood when the group = NULL note that this is used for other stats like median , mean , smooth etc.