all numberic value are rounded to a fix digit using ggplotly()

[laoyang945]

in Line 48 of layers2traces.R, in processing all all numeric variables are rounded to 2 digits. so the hover text for small value/closed value are non-informative.
It's desired to adjust the rounded digits in different applications.

example
df <- data.frame(x=runif(100)/1000,y=runif(100)/1000)
p <- ggplot(df,aes(x,y)) + geom_point()
ggplotly(p)