fix data labels
Add new dependency
Update Namespace with new function
new function cv.importance + documentation
generated documentation with ROxygen2
Add .gitignore
change version number + date
refactoring of validation to improve source code readability.
fix small bug introduced in refactoring
Documentation of the function
Merge pull request #124 from pommedeterresautee/master

Add a new function to see importance of features in a model