Quantile summary using dplyr

Say you want to compute quantile summary for multiple variables.
require(dplyr) require(tidyr) require(broom) As an example let us use mtcars dataset.
glimpse(mtcars) ## Observations: 32 ## Variables: 11 ## $ mpg <dbl> 21.0, 21.0, 22.8, 21.4, 18.7, 18.1, 14.3, 24.4, 22.8, 19.... ## $ cyl <dbl> 6, 6, 4, 6, 8, 6, 8, 4, 4, 6, 6, 8, 8, 8, 8, 8, 8, 4, 4, ... ## $ disp <dbl> 160.