Implementation Process - Data Preprocessing - PCA method

[antoinecarme]

Add PCA pre-processing method (Principal Component Analysis)

As described in issue #2

model  <- preProcess(iris[, -5], method = c("pca"))

References :

https://www.rdocumentation.org/packages/caret/versions/6.0-80/topics/preProcess

[antoinecarme]

Added data preprocessing with pca method.